No First Human Creature

There was no first human creature.

Human bodies evolved from earlier lifeforms, so there was no creaturely "first" man or "first" woman human being. There was no point in time, from a biological evolutionary point of view, where we could identify this creature to be the first homo sapiens sapiens creature (irregardless of its gender), while its parents were of some other species not belonging to the same species as the offspring.

Evolution is an incredibly slow process, homo sapiens didn't just pop out onto the earth scene one day, exclaiming "we have arrived!" Indeed, homo sapiens sapiens are physically made of at least 3 species of human being (and most likely more) - homo sapiens sapiens, homo sapiens neanderthalensis, and homo sapiens denisova - so we can't even really define "human being" as a creature belonging to our own particular species within the genus homo.

Homo is the genus of great apes that includes modern humans and species closely related to them. The genus is estimated to be about 2.3 to 2.4 million years old, possibly having evolved from australopithecine ancestors, with the appearance of Homo habilis. Several species, including Australopithecus garhi, Australopithecus sediba, Australopithecus africanus, and Australopithecus afarensis, have been proposed as the direct ancestor of the Homo lineage. Each of these species have morphological features that align them with Homo, but there is no consensus on which actually gave rise to Homo, assuming it was not an as-yet undiscovered species. [source - Homo]

Assuming for the sake of argument that homo sapiens sapiens arose through a single species-line of hominin ancestry (which is highly unlikely) and that that species-line was Australopithecus sediba (the most likely candidate known at this time), I must also point out that even though these direct-line ancestral creatures might be classified as something other than human, I think that it is very dangerous and foolish to minimize the contribution of "non-human" ancestors to our humanity. Indeed, these non-human ancestors form the very foundation for everything we are as physically incarnate creatures.

My thinking is that the soul is never fully incarnate in any body, including our human ones, such that even our non-human ancestors contained our "human" consciousness inasmuch fullness as the creature's body was able to tolerate - consequently, even our non-human ancestors were human in a manner of speaking. They are us, we are them.