Because we don't understand how they did it we don't have to start thinking in biblical explanations or green men of Mars.
How did the Egyptians build the pyramids? have 50.000 people doing the work for 20+ years and using crude but effective methodes.
Doubting our far ancesters and their will to make things happen and contribute their hard work to green men from Mars or biblical solutions is not the answer.
They were a lot stronger as us, more determinated, hardened by their life and if something had to happen, it happened.
Even if it took decades and a gazillion people to do it.
2000 years back we took our country from the sea just with a few spades and enough people to build levee's by hand or dig canals by hand.
2000 year later we have machines to do that work.
How did the Egyptians build the pyramids? have 50.000 people doing the work for 20+ years and using crude but effective methodes.
Doubting our far ancesters and their will to make things happen and contribute their hard work to green men from Mars or biblical solutions is not the answer.
They were a lot stronger as us, more determinated, hardened by their life and if something had to happen, it happened.
Even if it took decades and a gazillion people to do it.
2000 years back we took our country from the sea just with a few spades and enough people to build levee's by hand or dig canals by hand.
2000 year later we have machines to do that work.