It's been decades since I read this...but something made me think of it.
Here are my type guesses:
Piggy: INTp...He seems the absolute perfect INTp image.
Ralph: Probably E and F in there somewhere...maybe ESFp or ENFj or something?
The bad folks: ESTp
As I said...It's been a long time. Piggy's the only one I'm pretty sure about.