No, there was never a first human being. There was never a human being born to a nonhuman mother.
There was a graphic on the Internet I can't find again. It was a long paragraph of several hundred words that began in red text that gradually transitioned into blue text, and you were asked to identify the first blue letter. There was no first blue letter despite the fact that the piece began red and ended blue.
This is called the sorites paradox. You start with a pile of sand and remove one grain/ Is still a heap of sand? Sure. Now repeat, then again, until there is one grain left. Is that a heap? Not to me. When did the heap become not a heap?
I just had this discussion in a thread on the historicity of Jesus. Did Jesus live, or is he a mythical character? When skeptics consider the question, they remove the supernaturalism, and ask, apart from virgin birth and resurrection, apart from raising the dead, walking on water, and changing water to wine, did such a person exist? If so, I suspect that most people including atheists would say that a historical Jesus existed. How about if the other claims are mostly correct - maybe there were only eight disciples. Still a historical Jesus? I'd say yes. What if one were named Felix and one a woman? How about if we remove Nazareth from the story, or the Last Supper, or the trial by the Jews?
Hopefully, you see my point that there is no clear line. There are dozens of examples of this. When was the first second of your consciousness today, the one before which you were unconscious?
