You're quite right-- a LOT of things can be learned, up to a point. For example (of all things) I had zip aptitude for playing golf as a kid and teen, even though we lived next to a golf course. But through determination, I made my way to very near "pro" level.
That said, I do believe a lot of people have an "X factor" that separates brilliance from "really good." It's part passion, part vision, part "eye" and part something else... that can't be "taught." But it's probably only truly relevant if you're trying to win Olympic Gold at something....