Comedy is a peculiar thing. It is at once so universal that there is scarcely a movie made, from the most breathless actioner to the direst tragedy, that doesn't have its comedic moments, and at the same time so individual that there is probably not a single comedy movie made that every viewer agrees is funny.
What Makes a Movie a Comedy?
Another strange thing about humor on film is that it really can't be explained. A person who finds a movie funny simply can't explain why to someone who didn't. "It's funny because..." Well, because it just is. Or it's not. Highly individual. Physical comedy was the first to arrive at the movies. Buster Keaton and Charlie Chaplin didn't need a soundtrack. They could be funny without saying a word. Comics of the silents made comedy of the pratfall and slapstick variety.
Sound was necessary before the drawing room comedies of the stage could make the translation to film. Quips, bon mots, and witty repartee are better heard than read.
There's a flavor of humor for every taste. Put a sensible person in a silly situation, and that's funny. Put a silly person in a sensible situation, and that's another kind of funny.
A comedy movie doesn't require the protagonist to be a heroic or virtuous character. A tramp, a drunk, a shady lady, a wildly incompetent detective, can all find themselves headlining a comedy movie.
Many highly popular movies in this category appeal to a broad section of the viewing public, while leaving another broad section stumped and wondering 'what so funny about that?'. It's all a matter of individual preference, and while there's no comedy movie that every viewer finds funny, there is surely not a viewer alive who has never found any movie to be funny.