Smart isn’t one thing. Fixing a car and writing an essay are different kinds of smart.

Treating intelligence as a single quantity puts somebody at the bottom of a list that was never real. Finding a fault in an engine and building an argument in an essay use different equipment, different kinds of memory and different sorts of patience, and being good at one tells you very little about the other. Schools happen to measure a narrow slice, which is not the same as that slice being everything.

Name the kind of thinking you are genuinely good at, as specifically as you can. Then notice where you have been calling yourself stupid for being worse at a different kind.