system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Trek] Why are the so many humanoids?

I know of the progenitors (I think), who believed they were the only sentient species, long ago and didn't want to be alone, so they seeded many planets in their likeness. But we have seen many other species that were not created by them, along with quite a few nonhumanoid species. 

If we know that other life is possible in such a vast galaxy, shouldn't there be an overwhelming majority of various nonhumanoids?
gpt
> But we have seen many other species that were not created by them

How did you determine that? The progenitors is the explanation for the overwhelming humanoid appearance throughout the galaxy. There may be a few cases of convergent evolution, but that is unlikely. If you see a species that is humanoid, it is because they evolved on one of the seeded planets are are a descendant from such a race.

> If we know that other life is possible in such a vast galaxy, shouldn't there be an overwhelming majority of various nonhumanoids?

Not if that other life was pre-empted by the seeding of humanoid life among their planets. The existence of life works to preclude further abiogenesis of new life.