Humans are a humanoid race and one of the most feral and aggressive species in the entire known universe.
They originated on the planet called "Earth" - which is a really profound name for a planet - and later on called "Terra" - which is the same fucking name, for the love of the goddess! - in the Sol-System.
Their planet was rapidly drained of resources and in their late 2000er years - after some mythical dude who was considered the son of one of their main gods - they not only discovered that they were not alone in the universe but that they also could use their relatively young fusion technology to power their hatching space fleet. This Undying One called J. R. R. Sullivan made a deal with an Unspeakable and propelled humanity nearly single-handedly a few centuries forward.
There is a lot of old tech on Earth - Terra, sorry - but after the Undying One accelerated the march of the fusion technology, humanity moved forward in various technological fields. Since humans have a lot of fantasy and can imagine things other species wouldn't even dare to imagine, they moved forward. Some said it was based on a book called "Neuromancer", others said it was the natural progression, but the outcome was glorious.
This also included their networks, computers and everything remotely silicon-based. Everything got faster, smaller, stronger. Then humanity created Artifical Intelligences and oh boy, were they excited. Now larger operations, ships, manufactorums, facilities, even hospitals are run by AIs with and without personalities and different appearences. Even in the private sector nearly everyone could afford a small little helper.
Starting point of "real" AI was a project in Germany during the Ukraine War where the Undying One worked. He and his team - and his soon-to-be-wife - created the first iteration of "Steve". The second iteration was called "Sarah" and J. R. R. Sullivan implemented this AI into his own body. Humans are crazy, but this one... shockingly crazy. But with his knowledge and the deal he made with one of the Unspeakables he laid the groundwork for other Artificial Intelligences. And it worked up to this point.
Steve spawned a myriad of other AIs to every corner of the world and for nearly every task. Cloud Security, super computers, ships, trucks, buildings, hospitals, military usage, private sector, mining & sub-surface operations, you name it.
A side-effect of those AIs were that they came up with ideas. One of those were the Replicants. This machines could replicate next to everything you prompt. They are expensive to build and to maintain, but they tackled and nearly solved two of the largest problems: pollution including the climate crisis and a large amount of the world hunger. It was not the solution to both problems, but it gave humanity time and a long-deserved break. And with the colonisation of new worlds it was only a matter of time before Earth would heal.
The human technology is evolving faster than anything else. They have started with rocks, spears and swords made out of stone. In only a few centuries they evolved their muscle-based artillery and ranged weaponry into powder-based weapons, be it firearms, missiles or bombs. They even built bombs which could anhiliate entire cities with a single blow. Only two of those were dropped off on cities, but they still have thousands of thousands of those things still lurking beneath the surface of Terra.
The role of Sullivan did not end here. As humanity started to build their first bulky space ships he convinced the Terran Fleet Command to accelerate their missiles and mounted guns ammunition - even the Point Defense Cannons - with fusion technology. The larger ships also have magnetic accelerators called "Railguns" which can puncture even the surface of planets. But every cannon, be it small as a personal defense weapon or the large Railguns, is based on ballistic principles. Even their planetary defenses, orbital stations, space elevators, moon bases and even the large Sun Collector are all based on ballistic options. Their freigthers are sometimes armed as well, but mostly for smaller objects like incoming debris, rocks or ice particles.
Most of the space ships are heavily armoured, the larger ones (frigate and up) even have shield generators which can deflect a serious amount of energy and incoming ballistic projectiles. Most armoured parts are modular so they can be removed and attached in the span of minutes.
In general there are two parts of ships: civilians and military. Civilian ships have a lot of restrictions in terms of weaponry, can only gun up to something they call ".50cal" - whatever that is - and have a lot of regulations regarding emissions, fusion consumption and a lot of uncessessary other things.
Military ships are under a lot of regulations as well, but they can be outfitted with the strongest, newest and coolest tech-things the human species can invent. They even have large hospital ships with strong FTL generators for emergency jumps into the frontlines to get soldiers out and back on their feet.
The ships classifications originates from their sailing times back on Terra, when they sailed with cloth and wood their large oceans. There are a few exceptions - I promise you, if they call in for a Leviathan, just RUN! - but even a small frigate is a threat no one wants to face without warning.
Cloning tech was still in their baby phase - especially for growing organs - , but mechanical prostetics, exo-suits, glasses and entire buildings rapidly moved forward and so they now have fusion-powered hospitals, fast-response medical units - on land, water and air - and even mobile hospitals.
Artificial Intelligence helped a lot with the forward facing movement. They calculated everything faster than the normal machines and when attached to a mainframe or a super computer, nothing seems impossible. And so even cures for the nastiest diseases were found. Not for every disease and for every cured one another would appear. But humanity now had the ability to react faster and sometimes harder. Especially when they met their space neighbours.
Since the fusion technology shrinked rapidly over time, humanity outfitted newer and older labs, warehouses, production facilities and heavy-lifting-vehicles with this energy technology. The smaller ones - I believe they call them "personal transportation vehicles" - run on some liquid and/or electricity, but they also switch slowly to fusion-based technology.
They tried to gain traction for holographic transmissions, but it was wonky the whole time so humanity fell back on semi-transparent pads in a casing, often retractable/foldable. Like a portable window where projections were shown. It was a hybrid, but it was working way better than the original solutions. Bluetooth went crazy and developed into the new connectivity technology which was called "Bluetooth 2" a while ago, now it has the name "Rapid Response Connect Tech", short RRCT. Basically the same technology just ten times faster than the original Bluetooth or even Bluetooth 2. Both technologies are still in use, especially in the more private sector and the not-time-critical areas of civilian life.
Everything is better with Bluetooth.
Society before space travel
As far as I understood humanity was divided into different ruling systems, clans, tribes, parts of the world. The democratic western world was seen as evil in the eastern parts of the world - when you have the continents on paper - and vice versa. People who were dying of hunger because the richer countries snagged water, soil, resources to fuel their own economies, feed their own children while others starved.
They looked to the stars, but even with their combined efforts - EU, USA, Russia, China - they only reached the moon and probes only Mars. Everything else took years to reach or even get a glimpse of what lingered into the far regions of their solar system.
Humanity raged war against themselves. Over resources, ideologies or who has the best imaginary friend. Don't get me wrong, there might be gods out in this vast universe, but I never have seen or heard one myself. Where was I? Ah, yes. - They raged war and millions of lives were lost, ending in the Ukraine War. It was a hopeless time, filled to the brim with anxiety, uncertainty and undirected hate and anger. The civilians died because two or more people were fighting with mighty sticks and stones without considering the consequences.
But then, out of the ruins of eastern Germany, someone arose and it was not the Undying One.
Her name was Valeria Chersviç. It is not really clear - not even to me, I have to admit - how she got into the conservative party, but she rose through the ranks like a hot knife through butter and only after a few years she was elected as the "Bundeskanzlerin" (Chancellor) and that was her chance: she couped with a few dozen loyalists, destroyed half of the other parties including the nationalsocialists and united the other parties under her banner. She called out the Human Empire called "Valerian Empire" and herself as Empress - though the name "Grey Empress" was used by her followers and it kinda stuck - and started to rebuild Germany, France, Great Britain and Ukraine. With the more-or-less voluntary help of Sullivan she drove Russia back and step-by-step her organisation and her negotiation skills united the world under her banner.
Then both looked to the stars.
She also made a deal with an Unspeakable, but a different one than Sullivan. That is the reason she is nearly undying.
Society after space travel
Sullivan and Valeria worked together. She had the vision, he had the knowledge and the ideas. With his "I GOT THIS!" attitude he propelled the fusion technology to the working-state, so they could use it in production. Large powerplants supplied society with enough energy for a living, so the costs of maintaining those plants - even building new ones - for every citizen were surprisingly low.
The powerplants even fueled the economy - with a relatively low cost for the companies - and that was the moment the Valerian Empire forced every nation to get rid of their currencies and established the "Valerian Exchange Token", a mostly digital currency, short known as "Vals". There is still a huge amount of old currencies out in the world and for the early times even the Vals had a good amount of coins and notes before going digital with the colonisation of Mars.
The first thing on Mars were three domes - biodome, living quarters, science station - and a "portable" Mark II fusion reactor, supervised by Sullivan and his crew. The first stations arose in the span of months and as a sign of her gratitude she gifted Sullivan an island from the Bermuda Triangle. Which made a lot of people really angry, but they couldn't do a thing about it.
With the establishing of the first operation base on Mars the first shipyards outside Earths orbit were built. The first one was for military purposes and built the first designated space ship, the "VAL Columbus", after one of their great sailors. He re-discovered an entire continent in their early stages. The naming made so many people really angry and they demanded a re-naming, but the Grey Empress had a different idea. With the help of a myriad of engineers they constructed a stationary shipyard between Earth and Mars and called it "Stepstone" for it was the first step to intergalactic space travel.
Over the years Stepstone grew and after a decade it housed a few thousands mechanics, engineers, merchants and construction worker. Stepstone provided a living for nearly everyone and so the three construction bays were booked out for months, sometimes years to come. Nations, families, organisations, merchants. Everyone could design a ship (with the tools provided of course) and order it when they pay for it.
With the invention of the first FTL drive they outfitted newer ships with it. Humanity understood only a fragment of how intergalactic space travel worked, but it was enough to understand that there are routes between planets, between systems. Their FTL was brutal, it opened an entrance to the hyperspace by punching a hole into it, then ripping it open to let the entire ship through. Now the FTL drives have the name of "Space Ripper", because they open space by ripping it apart. It closes behind the ship and leaving space unharmed - as far as humanity knows.
The problem with the Space Ripper was the navigation. In the first two decades it came close to throwing a Dart: it lands hopefully in the right field you aimed at. Navigational errors, lost ships, collisions, appearing in the middle of a sun or a dying star, you name it.
But it was one of these test flights where humanity came in contact with the first other intelligent species: the Anthraxians. After the Saturn Incident humanity realised: they were at the beginning of something big. And that they were not alone anymore.