When I was a teacher, I was asked those things too.
Then one day, the question came phrased a new and better way: "What is this GOOD for?" The answer I gave then changed my life and thinking. I said quickly "So you can get more jokes." I think we were reading a simplified Romeo and Juliet at the time. I could've gone into literature and history and fine arts, but the truth is that the best and most immediate use of most random learning is that it illuminates the world. The more we know, the more jokes we will get.
To Get More Jokes
"Thinking and Learning and Bears"
by Sandra Dodd, 2007