The Miles from the universe where the spider never bit him, so nobody became Spider-Man, and everything went the other way.
Miles G. Morales is the Prowler of Earth-42, voiced by Jharrel Jerome. He is the same person as Miles Morales, in the universe where the spider that was meant for him ended up somewhere else.
He is the strongest idea in either film. Everything Miles is told about canon and inevitability is answered by one room: a version of himself who had the same family, the same city and the same character, and became this instead, because of a spider that took a different lift.
Minor spoiler
Without a Spider-Man, his city has no protection, his father is dead rather than his uncle, and his uncle Aaron raised him. Nothing about him is written as inevitable, which is the point being made against Miguel.