All humans trace their ancestry back to Earth. Some can even name countries and cultures they descend from, or which modern traditions date back to ancient times. Yet the Earth itself is a distant planet none have heard from in centuries, and few consider it worth the time to rekindle that connection. Most believe they're the lone living sapients in the galaxy, and it shows in their unrestrained exploitation of resources.
Culture
Each planet has its own cultural identity inhabitants relate to, but no planet is a monolith, and innumerable distinct cultures exist on each.
So-called 'spacers' living on moons, asteroids, ships, and stations define themselves differently still.
While there is a universal trade language, many use more regional languages to define in groups.
Religion
The most prominent religion is the Church of the Great Mother, which believes a goddess-like figure created the universe. The two most popular sects are near-opposites:
The Congregation of the Enlightened, whose core beliefs are those of repentance.
Planets police themselves, but some galactic organizations manage interstellar regions:
The Protectorate polices interplanetary politics and trade, but their efficacy has been in doubt.
Perimeter is a military group that seeks out and destroys egregiously harmful technology.
Mercenary groups like the Invincibles can be hired for protection.
Villainy
Whether due to selfish goals, aggressive means, or an intent to cause harm, others make life harder:
Piracy has surged in the wake the Protectorate's waning ability to keep trade routes safe.
Black market groups like the Syndicate seek out and provide dangerous tech and materials.
The Emerald Legion uses spies and underhanded tactics to get their way.
Current Species & Cultures
Aliens
Ruins from pre-human aliens known as the urahl dot various planets, the species having gone extinct an estimated 10,000 years ago. Xenoarchaeologists study the underground remains of the ancient civilization, hoping to learn something of who they were. Some computer systems and weapons remain, kept alive by self-repair technology still under investigation.
Inorganic intelligences encompass human-created systems that perform various work so their owners don't have to. Few people consider these machines sentient, much less sapient. Yet as humanity learns to encode greater intelligence, more inorganics are used for companionship, giving potential for change. Some groups have already started advocating for it.
This custom setting by Rin Garnett is based on and used with the Stars Without Number (Revised) TTRPG by Kevin Crawford (check out the free and full versions at Drive-Thru RPG). All page covers use art from the official art pack. Unless otherwise noted, all other art is by Rin using public domain assets.