I read something a while ago that really put all these “ancient mysteries” into perspective: Modern humans with modern brains have existed in our current form for at least tens of thousands of years. During that time we’ve seen huge advancement as a society thanks to the accumulation and sharing of scientific knowledge, but any individual human today has no more brainpower than one living 10,000 years ago.
In other words, if we can sit around today and brainstorm a dozen different ways to build a pyramid with nothing but ramps and levers, there’s absolutely no reason to think that the smartest builders in ancient egypt couldn’t have come up withl the same ideas or better.
Attributing these achievements to aliens, or divine intervention, or anything other than raw human ingenuity is a disservice to our ancestors.