I think to be human is just a matter of biology, of being a member of the Homo Sapiens species. If you're not scientifically a human, then you're not human. I don't think there's other "intelligent life" out there, but if there is, them not being human wouldn't be a bad thing; I know the term is "humanity", but if we're using it to mean empathy and fair treatment, then technically other forms of life could exhibit "humanity".