What's the goal of mathematics? Are we just trying to prove every theorem or find theories which lead to a lot of creativity or what?
I've already read G. H. Hardy Apology but I didn't get an answer from it.

This is not directly answering your question, but it might be interesting for those asking the question. One reason for doing mathematics are applications in natural science. I expected the article to answere more questions, but I want to recommend it, though:
The Unreasonable Effectiveness of Mathematics in the Natural Sciences
