The year is 1966. The animated special It’s the Great Pumpkin, Charlie Brown appears on television for the first time. The plot is well explained at Wikipedia so there’s no need for me to repeat.
This was a simpler time when people didn’t expect a lot of action or much of anything else in their cartoons. Not much happens. I guess it’s supposed to be amusing because of the cute cartoon characters, and you’re supposed to enjoy the accompanying piano-heavy instrumentals.
The main gags are:
1. Charlie Brown is a loser: a beta-male before the term was invented. Lucy tricks him into kicking a football she pulls away. When Charlie Brown receives an invitation to Violet’s Halloween party, Lucy tells him it was a mistake, and he was on the list of kids not to invite. Charlie Brown is unable to cut two eye-holes into a sheet to make a ghost costume, so his ghost costume is full of holes. When they go out trick-or-treating, the other kids get candy but Charlie Brown only gets rocks. At Violet’s party, they draw eyes, a nose, and a mouth on the back of his head because his bald head looks like a pumpkin.
2. Linus has the Great Pumpkin confused with Santa Claus.
3. Snoopy imagines that he’s a World War I flying ace, and his doghouse is his airplane. He gets shot down by the unseen Red Baron and makes his way across the fields of France, stopping for a while to pretend that he’s an orchestra conductor while Schroeder plays the piano. Then he shows up at the pumpkin patch where Linus is waiting with Sally for the Great Pumpkin to appear, causing Linus to faint.