If all you had was rocks, time, and wealth, you'd figure shit out too
Can't remember what that's from, but it's true.
Generations tend to get "smarter" but it's more about what knowledge they're exposed to, not that people are intrinsically smarter now.
The humans alive 6,000 years ago weren't stupid, they were just mostly uneducated. So when the smartest job was building things with rocks, a lot of really smart people figured out good ways to build with rocks.