You scoff, but when the Pyramids were built that civilization definitely knew that Earth was a sphere. Check out some of the work by Dr Graham Hancock and be prepared to leave dogma by the wayside. Here's a good start: https://grahamhancock.com/schmitze1/.
That’s why I suspect the Nephilim/Giants perspective might be more sound than we tend to believe. It nicely explains why so many pyramids, blood sacrifice, cannibalism, and images of giant gods occur in multiple cultures, along with the monolithic blocks and construction of edifices in remote locations with ungodly large monolithic stones, inexplicably placed with such precision.