This is a "Wild Mass Guess" entry, where we pull out all the sanity stops on theorizing. The regular entry on this topic is elsewhere. Please see this programme note.
Confessions of Georgia Nicolson
The books are extremely biased to Georgia's point of view.
Obviously, to be as funny as they are, some aspects about the books have to be a bit stretched. However, this theory could explain the borderline cartoonish personalities of many of the characters. If Georgia is irritated by someone, she'll stretch out their bad traits — these are her diaries, after all. For example: Ellen is depicted as (relatively) normal until she shows an interest in Dave the Laugh, Georgia's (eventual) Victorious Childhood Friend of sorts. Soon afterward Ellen's character is flanderized to the point of being a borderline stuttering fool. And perhaps Jas's tendency to ramble on about wildlife later on in the series is an exaggeration of how Georgia perceives it. Or maybe this was all extremely obvious and I was the only one who didn't catch it until now, in which case: oops.