I'm not certain who Larry Novak is without more context. He could be the author who created this original Christmas story, or perhaps a character within the story itself.
I'm not sure if there was a character named Larry Novak in 'A Christmas Story'. I don't recall such a name from the movie. It could be a relatively minor character or perhaps not in the movie at all.
Jimmy in 'Jimmy's Confessions' could be a character with a complex personality. He might be a middle - aged man who has led an eventful life. Maybe he's a writer who is using his confessions as a way to tell his own story, or he could be someone who has just reached a point in his life where he feels the need to unburden himself of all his secrets.