Yes an RP can function with only one species, and honestly I don't even see it as a creativity killer.
The majority of RP's that exist expect everyone to play as a human, like if I randomly made a wookie in a High School RP people would probably go "Say what?".

If you have an RP with only one species but said species is alien and not human? In my mind that still gives more creativity because you at least have a brand new species to work with and roleplay with rather than going with traditional humans.

And yes, all the players should be able to play the same species fine. Cause once again, we do it all the time as humans.