I remember a lecture in a psych class about humor. Of course what is funny to one person might not be funny to someone else. We have differences in our responses to humor because we have different anxiety levels, and get more or less tense or anxious about different things in accordance with our experience, values, etc.

In order for a joke or anything else to be funny, it must create an increase in tension, and then a release of that tension. It is the release of tension that we experience as humor. But it only works if the levels are appropriate for us. If it doesn't raise tension enough, it isn't funny (the joke goes over 'like a lead balloon." But if it raises tension too much, then it isn't funny because our anxiety level is too high and stays there.

For example, to little kids, a clown whose pants fall down might be hillarious. That's something that little kids might relate to and feel some tension about, and when it happens to an adult, it releases the child's tension about being in that situation themself. Most adults don't get as much from that clown routine though, because we don't have issues with our clothes falling off, so it doesn't raise our tension level and there is nothing to release.

And when a joke hits too close to home, it isn't funny because it offends us and we stay offended. Or if it scares us, etc. That's why humor must be sensitive to the audience it is presented to.