Moving the stones was probably easier then thought, because Wally Wallington (?) was able to move stones that weighed over 10 tons by himself with little difficulty.
Here’s an oral account of someone moving 16 tons by himself.
https://m.youtube.com/watch?v=RRh0QiXyZSk
Interesting.
Well, sage wall looks like stonework to me. I do not look down on the people who came before us as incapable of doing large stonework, but it would be neccessary (as several have stated above) to do some excavation for additional information. Discarded Iron tools? Broken Pottery from the Stone masons? Bones telling us what they ate? Skeletons from the people who lived and died on the site?
I think that there was also stonework high in the Andies looking down at the Amazon basin about which we know nothing.