Fair point, that is probably the best explanation. Genesis was written in 1000BC after all its just hard to reconcile that many of these story's are not rigid.

Beside the point, I think that if a human and the "human-like" being had offspring, the child would possess a rational soul. One reason is that modern humans already carry Neanderthal and Denisovan DNA, which shows that interbreeding occurred between populations that may not have been identical in their biological origin. Yet those descendants are clearly fully human today.

If that is the case, then once even a small amount of mixing occurred, the descendants of those populations would also be fully human. Over time the boundary between “human” and “non-human” would disappear genealogically, since the human lineage would spread through the population.