During a seminar in grad school, a professor asked a group of us if we ever used humor in our writing. When he looked to me, I blurted out, "I'm sometimes unintentionally hilarious, usually for the wrong reasons."
The thing is, whether unfunny people like me like it or not, funny moments are important. They can highlight a new aspect of a character's personality, break the tension in a serious scene, or help you draw readers into the story. Humor can be applied to any form--poetry, fiction, non-fiction, and beyond. Even the most emotionally fraught tale will have room for comedy, however brief the appearance.
You should try your hand at this sometime. Don't force it; just write what comes naturally. Run it past some trusted friends. If it's not funny, try again. I know you have the humor in you somewhere.