system
Given the following post, respond as if you're commenting on Reddit:
human
[Alien Universe] How many species has humanity found in the universe?

Was the discovery of the xenomorph/space jockey our first contact? How many species are there in the Galaxy?
gpt
Arcturians are apparently a humanoid and sentient species, and apparently they were our first contact according to some extended universe stuff.   The marines refer to a "bug hunt" as well, so presumably we've encountered several non-sentient aliens as well.

No telling how many other races though.  Just that Space Jockeys and Xenos aren't the first.