I think I was better than most kids at math, particularly algebra, but those kids grew up and caught up and I suspect many of them are as good or better at math than I am. I know nothing about child psychology or anything adjacent, but I honestly think a lot of "advanced child" stuff is just maturity.
That makes me think back to my elementary school, where a lot of the kids who got into the "gifted" program just happened to be, surprise surprise, some of the oldest kids in their grade.
At that age the better part of a year in brain development can be exactly the "edge" one needs to excel. And then it can become self-reinforcing when kids gravitate toward the areas in which they dominate their peers.