Genre
Fantasy, Fairy Tale, Comedy
If Time Bandits fits into any specific category, it's fantasy: the map is essentially magic; monsters and giants are actual things; mythic figures like Agamemnon are presented alongside legends like Robin Hood and historical figures like Napoleon; and whenever reality gets in the way of the story, it's jettisoned in favor of the fantastic.
The film is also a fairy tale. Fantasy and fairy tales are natural siblings, and while this one often treads down the darker side of the path (that part where kids get burned up in ovens so witches can eat them), it understands the landscape pretty well. There are ogres, after all. And dark fortresses. And lessons about being brave and staying true to yourself in wild lands where magic is around every corner.
Finally, since this comes from the Monty Python boys, we can't ignore the funnies. Everything in the film has a slightly absurd bent, and while the scenario itself is taken seriously, Gilliam and his crew take the time to remind us how foolish these characters can be—and, by extension, how foolish we all are—while giving us a fistful of giggles. That's just what these boys do.