“It is sort of a fantasy jazz camp,” Banu Gibson says. “Our campers are people who are investment bankers whose parents told them, ‘No, you can’t be a musician for a living.’ Now they are going back and saying, ‘I’m going to do what I wanted to do.’ We get a lot of people who were players when they were younger and want to get back to it.”

Gibson’s referring to the New Orleans Trad...