We discovered one of the postulates was really interesting to fuck with.

It's better to say that we've discovered more math, some of which changes how we understand the old.

Since Euclid, we've made discoveries in how geometry works and the underpinnings of it that can and have been used to provide foundation for his work, or to demonstrate some of the same things more succinctly. For example, Euclid had some assumptions that he didn't document.

Since math isn't empirical, it's rarely wrong if actually proven. It can be looked at differently though, and have assumptions changed to learn new things, or we can figure out that there are assumptions that weren't obvious.

The number of hypotheses we've proven, mostly. Also, we have this whole field of non-Euclidean geometry. And the modern Pythagoreans are a lot more chill about people knowing the irrationality of Pi.

Yes, some of the shit he wrote was basically meaningless (the "definitions" before the axioms) and we would just leave it out.

Nope. Thats why I gifted it to my son, who studies math.

Not sure, I've only gotten to the middle of the third season. No spoilers, please!