What does qua mean?

"Qua" is a latin term now used in philosophy. "Qua" (pronounced "quay") roughly means "in general". Therefore "humans qua humans" is a fancy way to say "humanity in general" (all of us, no divisions whatsoever).

It can have a few different valances depending on its usage though, so I recommend looking it up in contextual use and in dictionaries before adding it to your lingo, it might impress people at a party, but if you use it incorrectly you might get called on it. Ouch!