- Comedic tone. We know (even if the characters lack of sense of scale) that the characters' troubles are harmless and funny, and can laugh at them. More importantly, it is clear from the delivery of the work that we're not expected to see these conflicts as life-or-death struggles.
- An compassionate character. This is probably the critical piece of the puzzle. Bertie, spoiled nitwit though he is, gets into 90% of his scrapes because he is trying to do a good turn for one of his equally dim friends. On the rare occasions when he acts with something in the general vicinity of malice, it's in a playful spirit lacking in the desire to do actual harm (beyond puncturing the occasional hot water bottle). He genuinely cares about other people's happiness, and that makes it easy to sympathise with him.
- In-universe insulation. Unless it's in the context of satire or bitter social commentary, it's a very hard sell to show characters angsting over trivial troubles while the world is falling apart around them. If your characters live in a world which is largely insulated from these issues, however, the audience's mental sense of scale is reset. If someone's love life is the most serious business at hand, we can forgive a lack of larger perspective.
If we can laugh about the characters and enjoy investing ourselves in their adventures because no one is going to get hurt, it is great fun.