To add to what Cairos said, try shifting his weight a little more so that he looks more bouncy. Right now his pelvis is almost stationary, which adds to the feeling that he is walking instead of shuffling. A little springiness might help get his groove on. Have you been using references while animating? Try looking at a few different ones. Even though you said he's shuffling, looking at Psy's "Gangnam Style" dance might help too, since they're pretty similar.