One thing I've found when writing comedy is that the main character often ends up slightly less funny than peripheral ones. Not a worse character, you understand, they still fill their role, and are in some ways much more complete, but less funny. The funniest characters in my current (well, not current, because I'm not working on them, but you know what I mean) works are definitely not integral to the plots, but the books would be far more sensible places without them, and none of us wants that.
Maybe their lack of importance is the point. Main characters have to go around being well rounded. They have to behave in ways that make some sort of sense, and they have to engage with plots that are not inherently ludicrous. Less important characters can be stretched almost to breaking point, can take on ludicrous story lines, strange obsessions, and all sorts of other things that we would never dream of doing with main characters. We can also make them look utterly stupid without having to worry about whether that is damaging the emotional impact of their presence, which leaves me nicely free to occasionally have them run into things.