"A Charlie Brown Christmas"- in the form of a random thought by Mckenna

So last night my mom, brother, and I watched "A Charlie Brown Christmas", the one from 1965, and in my opinion the best.  But I have one thought running through my mind about it- it's common knowledge that Charlie Brown is chronically depressed.  But even on Christmas.  And even Snoopy laughs at him.  I don't understand.  Can't... he be happy just one day a year?  Well, it isn't that I don't understand depression.  I've known people who have had it, but Charlie Brown is a cartoon.
Although, I do like the ending.  A lot.  When his friends stopped laughing at him and made his sad little tree look like something amazing, it really helped to portray how much friends can do for someone.  And Charlie Brown was smiling, then.  I know it isn't real, but the ending makes me happy.  Every year.