I've been a fan of anime since Star Blazers in my childhood, but... I wonder about an overused cliche in anime action-adventure series: teenage prodigy heroes.
For example, the most popular action-based anime (as opposed to comedy or relationship-based) currently on Netflix and Hulu (as well as StackExchange tag frequency): Attack on Titan, Black Butler, Bleach, Death Note, Fairy Tail, Fullmetal Alchemist, Knights of Sidonia, Naruto, One Piece, Sword Art Online. All of them feature unusually capable teens as the lead protagonists. Adults are supporting characters, or entirely absent.
Certainly there are exceptions (Samurai Champloo, etc), and this trope is also seen in the US (e.g. Adventure Time, Avatar, Young Justice, etc) but it's a matter of degree. Non-child heroes are not a rarity in western animation (Avengers, Batman, Tranformers, etc).
Is this a real thing in Japanese culture, and if so what does it mean? Or is it just a USA-based artifact of marketing (i.e. this particular subgenre is actively emphasized for translation) or audience (i.e. non-child anime is just as common but has less active fans)?