We could definitely make the argument that the narrator is a guide in a very literal sense, since he guides us through the story. But we think Creole functions as a different, perhaps more important kind of guide. He's a teacher and a mentor to Sonny. He guides Sonny and the other musicians through Sonny's first performance after being arrested. He literally guides Sonny onto the stage, but also leads him to a safe place (so to speak) in which he can lose himself in his music. And he teaches the narrator how to see Sonny in a new light. Creole functions as a sort of spiritual guide in the story, which is precisely what Sonny and the narrator need.