much is still unclear about the ancient times, and they/we still discover new stuff about the ancient. Like for example Göbekli Tepe. Göbekli Tepe is are ruins in eastern Turkey near the Syrian Border. Göbekli Tepe is at this moment the oldest temple complex in the world.
Much is still unknown about Göbekli Tepe or about the pyramids or about Stonehenge.
You sometimes see those ancient sites at the Ancient Aliens show on National Geographic.
And yes there are people who believe Aliens in one way or the other may have something to do with it.
To be short. I am not a believer in ancient aliens. Ancient Aliens Could be true. I don,t know. a lot of it has been based on Zecharia Sitchin work.
Sitchin work is known to be pseudoscience. His stuff is based on translations of Sumerian clay tablets.
I do not read Sumerian. Sitchin can tell me anything. it,s the religious old trick. Trick them with books they can not read. Lucky for me/us there are people that do read it. And all those people say Sitchin is making things up.
Despite all this there could be aliens. Who knows.
When there are no aliens to build these structure the humans did it them selfs. I think it,s more likely it,s build by people.
People who must have been sophisticated and far from far from savage.
The ancient cave paintings also where for sure not made by a bunch of unsophisticated savage caveman.
in the most ancient times there where subspecies of humans. The Neanderthal and other species of homo.
The name homo sapiens (wise homo) is a bit of a species ego trip. Calling yourself wise, as if the other homo,s where dumber then us.
I think that some of these other homo,s may have been very intelligent.
People went from a hunter gatherer lifestyle to a agricultural lifestyle and mindset. I think the rise of agriculture made a whole new type of man. With a whole new type of mind.