The ability to make oneself the butt of the joke is not humility — it is a kind of strength that wears humility's clothes to move more freely. Nasreddin lost his keys, forgot his arguments, fell off his animal, and was consistently outwitted by his wife; all of this made him more trustworthy, not less. The person who can laugh at themselves has already survived the worst that embarrassment can do.
Each step builds on the last.