I think it was Teller who said the secret to a good magic trick was to put in so much effort that no reasonable person would assume that’s what you’d done.
If you wanted to join a bunch of stones so well that there were no seams, using manual labor, would you pick shapes like these to confuse the hell out of future humans who would wonder how you did it with manual labor ?
Humans have been artists and show offs as long as we’ve been human. I don’t know if the craftsman who cut that thought people a millennium later would still be impressed by it, but I’m sure they’d be happy as hell that we are.