I think the premise is that the Predators built pyramids as hunting shrines for rights of passage rituals for younger Predators. Humans came along later and messed it up-now there’s too many hosts for the aliens and they breed out of control. The Preds go nuclear and the civilization that had sprang up is annihilated. Certainly a stretch, but not as far out there as some of the other ideas.

My guess is that they put the pyramid thing at the south pole specifically to AVOID human interference from mucking up another hunt.