Jimmy Corrigan never had a father. He and his mother were abandoned. Jimmy always wandered what his father looked like. He had numerous thoughts running through his mind about who his dad even was. This is what i would like to talk about here. They say that all young men grow up to be their father. This comes from Freud's theory about how boys will imitate their father's actions to try and impress their mother, but that's beside the point. The point is that Jimmy Corrigan had no father figure. He had no one to teach what it means to be a man. He was alone in this world with nothing but his mother, and a vivid imagination.
So what did young Jimmy do to try and have a father figure? He let his imagination run wild. He uses the image of Superman as a potential father. Maybe his strong liking of the cereal Captain Crunch was also a father figure. We see him eating it within the first few pages when he was a young boy. Then we see him eating it again later as an older man. Maybe this was his imagination at work. Maybe he felt that since he had no father, the Captain on the cereal box was his "dad."
Or perhaps Jimmy just liked that particular brand of cereal. Either way he uses his imagination to try and figure out who his father is or could be? All kids use their imaginations, and I'm sure there are fatherless or even parent-less children out there that do the same thing. But why does Jimmy use fictitious characters as his "father?" Perhaps Jimmy feels that by seeing his father in this particular way, he can feel better about him not being around. Maybe Jimmy just does not want to realize the truth of the situation. Or maybe, just maybe, viewing these characters as his father will give him the male role model he has been lacking all these years?
Well, as we see later in the comic, Jimmy imagines killing and scalping his father. I don't think Superman or Captain Crunch would necessarily scalp a man with a piece of broken glass. Now what kind of role model would show someone how to do that? A sick one, that's for sure. Jimmy needed a role model in his life that would be beneficial to his growing up. Superman is a good choice but he isn't real. He can't teach Jimmy how to fish, hunt, shoot a gun, play football, etc. He doesn't teach Jimmy anything.
Jimmy needed someone real and the only person there was his mother. Now some single parent boys, raised by their moms, turn out to be just fine and others turn out the way Jimmy did. They turn out sheltered and afraid to leave the "nest." They have no sense of freedom as they get older because mommy is always hounding them to do this and that.
Not having a father figure hurt Jimmy so much psychologically that he dreams about killing his dad. No son should ever dream about that but it all starts with the dad being a man. He has to take responsibility in raising his child and telling them he will always be there. Unless, he wants his children to turn out like Jimmy Corrigan, the smartest kid on earth.