You know, I have the film on DVD, and I watched it up to the Somebody to Love part (I'll explain in a bit), and it sort of struck me how very AS-like Mumble is. Especially how it's explained he went off into his own world when he was stuck in the back of his class. I'm like that sometimes.
And here's one thing I just thought of: the other penguins (save a few, especially Gloria) ostracized Mumble for his foot condition and terrible singing, but they don't mock him for his appearance, at least when he's a teenager. I mean, he looks exactly like a bigger version of when he was a baby, while the other penguins look fully developed. Guess that's what happens when your father drops the egg...
As I said, I only watched up to the Somebody to Love part because I was sampling the first 30 minutes of it; I'm planning to watch the entire movie on a triple bill with Xanadu and Joe Versus the Volcano. Three different fantasies, each about a character at odds with the world, and every film has polarized audiences. Sounds good, no?