Hmm, I've gotten my pirate to a slightly higher level then my age, but only by a few digits. My early elementary school aged son also plays (but has trouble quickly typing responses to questions people ask him).
I really wouldn't worry about the average age. Disney can't even begin to tell you what it is since so many put a fake birthdate in. There are definitely lots and lots of Peter Pan Syndrome adults out there along with lots of younger kids and tons in-between. It's the people that you meet, friend and have fun with that matter. Honestly, since 99% of them you'll never talk to outside of the game, age is irrelevant as long as you share the friendship bond and work together within the confines of the game.
Good luck and happy questing and leveling.
