As the offspring of biologists, I’m aware in the back of my head that alien life is unlikely to be humanoid, but aliens that look like people (or people in fx makeup, or people wearing animatronic masks, or as of Battleship people rendered in CG who look like people in fx makeup...) are such a mainstay for many reasons, practicality being an obvious one in live-action media but relateability being a factor as well.
So how does one rationalise, say, four sentient species of oxygen-breathing endoskeletal upright bipeds working together?
Well, for starters, let’s assume there are another half-dozen allied species who aren't like that, and they tend not to work on the same ships as the people-shaped species.
When considering a Star Trek game and factoring some of the unused ideas into Distant Stars I suggested going a bit further but not too crazy. So the Proud Warrior Race are seven feet tall and have four arms, which is about half as crazy as the Tharks. And the Wise Old Race are insubstantial.
I still want to find a place for Mr. N though. If R2 and Chewbacca can do it, so can an NPC on the bridge.
“Suggestions, Mr. N?”
Flashes and a slight change in humming tone from the column of light in the corner.
“Agreed. Charge polaron array.”