My brain tells me that the two biggest stories in New Orleans music right now are Hurray for the Riff Raff and Trombone Shorty, but in a year when I didn’t see Shorty, I started to wonder if I overrated him. Sunday in his festival-closing set at Jazz Fest, I was more impressed than ever. The show wasn’t ambitious. Shorty didn’t try to cover a lot of musical ground. Instead, he concentrated on simply being remarkably funky.