It would be a really fun idea to figure out how would the greeks and ancient civlizations would react to set theory as a foundation for mathematics. The greek in particular with their geometric bias I find it would be a bit hard to convince in light of the apparent contradictions that show up.

But I wonder if there would be a point in between where you could try to formalize a geometric algebra ( like in Artin's book ) and convince them that this makes sense and see if maybe that kickstarts some giant development more algebra focused than geometry/analysis focused as we had in history.

On the other hand Id be too woried to introduce my own biases , I think I would be much more curiou to learn about how they think about things than me trying to set them on my 21st century ways.