There is no way it was copper chisels and diorite pounding stones.
The scoop marks? Perfectly cut and polished stone boxes? 1000 ton pillars? Stone jars so thin they can be seen through?
No way it was copper chisels and copper tube drills with sand.
Look how [bleep] 50 year old "history" is widely taught to have happened today.
Extrapolate thousands of years...The amount of knowledge lost over millennia really can't be comprehended.
How many men alive can produce something as simple as a wooden bucket that coopers of 120-150 years ago would have knocked out multiples a day. Aliens didn't beam down bucket tech for us.
European trade guild system let all kinds of knowledge die. Masters unwilling to teach secrets that would potentially leak to competitors. Poof, gone.
You've also got the Younger Dryas Impact theory. I tend to believe its more likely that humanity has seen extreme rises and falls in population and accompanying technology over a larger span of time than previously thought. Its cyclical. Population and technology peak, boom - cataclysm, survivors launched back into stone age all tech and knowledge lost, start over, rinse repeat.