He’s a Mary Sue. I know that term gets misused by misogynists for, “female character I don’t like,” but it was originally a term for Trekkies’ self-insert fan-fic characters, and Wesley fits the trope perfectly: the youngest, smartest person to graduate Starfleet Academy/serve on a Starship, with unusual skills or special talents, who the ingratiates himself with the main cast, and finds himself at the center of major events despite his young age and low rank.