When you're very little (like 5) you watch Peanuts (Charlie Brown) cartoons and it's a little bewildering. There are lots of kids who are all virtually identical except for having different haircuts and t-shirts. They all talk as though they're adults to the point where there is no need for adults in the cartoon. So, the main story is just not accessible to little kids.
Luckily, there's Snoopy. He doesn't say anything, he just does what he feels. When things get dull, he escapes into a world of fantasy (Red Baron, Joe Cool). Little kids can relate to the bewildered, fantasy-addled Snoopy. In fact, they love him. You've never seen a plush Charlie Brown but you could choke the grand canyon with soft cute Snoopy dolls.
We spend years watching Snoopy's hijinks while the Peanuts characters are just background noise. But sooner or later, you start thinking about what Charlie Brown is really all about, the sheer sad disappointment of life. Unrequited love, perpetual failure, cruel statements, competing circles of friends are all the substantive material for this "children's" show. Charlie Brown and the gang become a cartoon boot camp for kids about to enter the real world or junior high (whichever comes first).
I have to extend a hearty thanks to Charles Schultz for this shell game that traded the whimsical for the existential. It allowed me, when life dealt me it's first cruel blows that my parents couldn't fix, to find the right words: "Good Grief!"