"They're my friends... I made them"
These are the "humans":
J. F. Sebastian, a genetic engineer working for TYRELL, made "friends" like this one.
Tyrell, the genius behind the replicants, father figure, and god.
Deckard, the protagonist, a reluctant Blade Runner who must track down the replicants, only to discover something more about them and possibly himself.
Gaff, another Blade Runner. Wherever he appears, so does his origami.
Humanity is the basis of identity, and this identity is unstable. As modernity shifts into postmodernity the gaps in our identity widen. Human, once taken for granted, is becoming more basic (base: foundation) as a means of determining who and what we are. What other options are there? The replicants are one, and those who create them have found another.