re: How did I learn how to listen to a joke?

Because the good joke tellers/storytellers were good enough that you just did all of those things naturally. They keep your attention, they have good timing, and they know what jokes or stories are worth telling. Everything else just falls into place.

I had great uncles growing up who were all great storytellers. They all loved to tell jokes, too. They could sit around a table for hours telling stories.