no it's just the fact that you need to avoid people or things that look deformed or odd because they might have some disease or something that might kill you too

It doesn't explain the uncanny valley at all. Were unsettled by things that are near human must not, not deformed or ill humans.

maybe it's because when you see something similar to a human you expect it to be human but you detect something is wrong and you become scared
maybe it's because as a species we care about our own species more than other animals
even if we saw a slightly off animal we wouldn't care because it's not us

I don't think you understand what uncanny means...

something strange that disturbs someone

Not quite. It means something that appears human but just isn't and it unsettles you.

there were things like that, but we killed and absorbed them