I'm very good at doing highschool math - which is, following basic pre-taught instructions to arrive at certain answers. I'm even decent at the slightly more open-ended geometry proofs, if only because I'm practiced so many of them I've developed a gut intuition as to what 'tools' to use when solving what type of problem.
But when I went to college, everything broke down.
When a professor writes a proof on the board, I GET it. I understand it, even on an intuition level (although sometimes only on an intuition level). Same goes with all those math channels on YouTube. I get what they're saying, I get how they reach all these conclusions. And yet, as soon as I'm faced with an open problem (even something as "simple" as proving root-2 is irrational) I'm completely stumped. I have no idea how to begin to approach the problem. It's almost like I like lack CREATIVITY to solve all these proofs.
How do I stop being such a brainlet?
You kind off answered your own question, you need more CREATIVITY
I had the same experience OP. The only advice I can give you is practice solving/proving theorems
>How do I stop being such a brainlet?
Practice. It's the only way anyone learns that shit. Get your favorite textbook of math that defeats you, and to all the exercises. Yes, all.
Anyone else bothered that all of combinatorics/etc is in one single thing in that image, yet single topics from other fields get mentions? (ie metric spaces, euclidean space, homeomorphism, etc)
one time pad decryption is impossible