Not your ability to tell jokes, but your ability to appreciate the funny stuff in life. Humour is all about being flexible and understanding several different meanings to the communication you get. The more brittle your are in your reality tunnel (map of the world) the less humour your will have, the less flexible you will be and the less choices will be available to you.
Improving your sense of humour is all about understanding phonological ambiguities. Phonological Ambiguities are when 2 words sound the same, but have different meanings, for example, right/write, eye/I, etc.
To improve your sense of humour, make a list of, say, 50 ambiguities. To start with. And then add to the list as you find new ones (there are 1000’s!) and find your sense of humour improve, your flexibility improve and your life get more fun!!