mean you can go with aliens, although as they say, “Just ’cause white people didn’t do it, doesn’t mean it was aliens”.
But we can thank Egyptian architects for the plumbob and for surveying. We can also thank other Egyptian smarts for hieroglyphics. For mummification. lots of stuff.
Heavy weight of stone pushes any gaps together.
Shape itself is logical for self-supporting: consider ALL of the failed pyramid shapes.
You don’t see them because they were the failures.