Well we have been great. While there were some great engineering behind those structures it was absolutely possible that they have been built manually. I saw many examples of ancient stonework that show sign of some sort of mechanical operations. I think anyway that we try to explain that with our tech while they had another kind of tech that we totally lost. I don't think they had motors or engines. The few possible electricity uses look like high tension low current. Possibly used for some sort of lights but probably not suitable for producing mechanical work.