Since the title of this thread: “Do only humans have souls? / How were humans ensouled in an evolutionary process?” involves questions of Metaphysics, the answer will vary from denomination to denomination, and even from person to person.
Metaphysics, or literally “Beyond Physics” or “After Physics”, touches on topics that cannot be verified with science.
So the only way to answer such questions is to either visit the afterlife and come back with a report, or to imagine how Christian theology affects one’s concept for how things work.
For example, does God literally construct one’s soul, and then connects it to your body?
If so, when does he do that? - - while you are still in the womb, or at the moment of birth, or at some later time?
If you have a really strong view of such matters, how would you prove it? Or how would you at least say you have a “clue” for why you hold to one idea/version versus a different one held by a friend?
In a different thread, I got into a discussion about whether or not a person “sleeps until the End of Days” - - to be re-activated during the drama of the General Resurrection? The alternative scenario was that the recently departed person, at least temporarily, exists (and is awake at least most of each day), without a material body until the drama of the General Resurrection.
It immediately descended into a person viewpoint that didn’t seem to be connected to any particular evidence … other than how Hebrew words are defined.
There’s no way to know for sure it seems. And the same goes on the question of the possession of a “soul” or not.
@Reggie_O_Donoghue, considerable progress can be made if you agree that God makes each person’s soul. Do you support that idea? Or do you think the “soul” is naturally created, through natural processes, even if there wasn’t a Yahweh to do it?
Depending on how you answer will significantly influence the answers that can be offered you.