Why does everyone build pyramids but invent different gods?
When people face the same practical problems with roughly the same resources, tools, and conditions, they tend to come up with the same solutions. Not because they learned from each other, but because people are lazy: nobody wants to waste more effort than necessary. Take pyramids, for example. If you want to build something huge out of stone without modern engineering, a wide base and a narrow top are a pretty obvious solution. You do not need Egyptians to teach you that. And reality gives you feedback. If something does not work, you try something else. But when people try to explain things they cannot test, all bets are off. The human brain hates not having an explanation, so it makes one up. And if there is no way to prove it wrong, any bullshit can survive for centuries. That is how we get thousands of religions, myths, and superstitions. They still have things in common, of course, because human brains work in much the same way. In short, reality pushes people toward similar solutions, while the absence of reality checks gives bullshit endless room to grow.