Actually in ancient carvings from around the world there are images of what could be beings not of this world. Just sayin............You really like false equivalencies, eh?
We have lots of proof of UFOs, including photographic and radar.
We have no proof that they're alien in nature. At least not yet.
Without any evidence that aliens exist, why would it even be a theory to suggest they played a role in shaping past civilizations?
As for how the boreholes were created, it's pretty easy... They used a Dewalt hammer-drill with a masonry bit, cordless of course, since they didn't have electricity.
It was brought back in time by people from the year 3000, and then they took it back with them.
Prove me wrong or accept it as another "reasonable" theory.