I get this. I had absolutely no interest in math in high school. And the little interest I did have, was to pursue other things such as engineering or sciences. And yet I found myself declaring a math major at the end of my sophomore year. Feynman once said “What I cannot create, I do not understand”. And I really took this to heart, and feel it deeply (it sounds like you do too). However, something we just need to accept to make great progress (unless we’re a prodigy like Feynman), we can’t literally reinvent everything. We can try to put our own spin on things here and there, and those are some of life’s delights. But the books written by mathematicians exist for a reason, take advantage! We have the nice ability to greatly accelerate our learning using these books. Although it’s not quite the same as completely coming up with it on your own, it’s still very satisfying to wrap your head around the concepts and results and proofs, and to be able to understand them well enough that you can reproduce the arguments on your own without referencing anything. And this is still a high bar to hit, it’s one I’ve accepted I should go for at this point, and I encourage you to strive for it too.

But anyway, you can do this. If anyone says you can’t do math unless you were planning to do it from a young age, fuck what they think, they’re wrong. Anyone can do it with hard work. Good luck.