Is there a usual, widely used word (a noun) in English that can mean a nice/cute/etc cat and a nice/cute/etc guy as well (internet slang, maybe)?

Solution 1:

pussycat

humorous: someone who is surprisingly gentle:

-Cambridge online

I guess you could say..

I just see a bunch of pussycats.

Darlings

I just see a bunch of darlings. ie, darling cats, darling guys.

If that’s what you are asking?

https://www.thefreedictionary.com/darlings

I would say "cuties"! If they are all cute, then they are cuties regardless of their species.