What are my chances at 2nd-tier math and cs schools like Cornell, Northwestern, and UMich?

AIME (or even USAxO) is not a hook. Not even a tip. OP’s nudge (not a tip, just a reason to keep reading, ) is the history. But the rest seems all about how he’s top at this or that, has some award. Not enough for a tippy top. They want to see more than the “Look at me!” aspects- i.e., the real kid who can get past that and show attributes they want. The kid who has humility (and it shows throughout,) isn’t all about “impressing.”

I often feel when any kid leads with stats, wins, and titles, he doesn’t understand enough about what tippy tops want.

Adding: Holistic. Not hierarchical. Think about it. Cuz it’s one thing that can block high stats accomplished kids from an admit.