Mercurian

The guardians of Mercury Depot come in many shapes and sizes, but in the end they all are part of the same cultural group, which makes them interesting. Rather like an intergalactic monastic order, people of all shapes and sizes coming together for the singular purpose of creating and maintaining portals to go on this immense ship.
The most common species are humanoid bipedal, since those are the species most likely to need a set portal network instead of using some other significant technology.
Honestly, they ought to be considered an organization, but none of them get paid specifically to be there on Mercury Depot, and with how big the station is they're practically their own country. All bonded together over the idea that they wanted to live on the world's biggest middle ground.
A lot of them tend to operate as diplomats. Most eschew all ties to their prior culture and it only really comes up if they know something about their home culture that can help in a diplomatic situation.
Most of them have some kind of technical background or physics knowledge. Something to maintain the ship and also to figure out the portals and keep them stable and secured and to avoid them all exploding in a way that would be bad for an ever increasing swath of the galaxy.
Their general knowledge of languages is one of their chief accomplishments, and definitely the one they're most proud of. The station itself came long before them and will likely last long after them, but each individual Mercurian can be quite smug about the broad collection of languages they personally have learned, usually a lot more than the average person passing through.
Their well-traveled worldview can actually make them rather smug in general, come to think of it.