a dream of a kid . remember the bum who sell manual . if the story about sing really happen and bum shall be some 20 year old than he first show up when sing be a small kid . but at the end part and he look the same age with before and try to sell some more powerful kung fu manual . there may be other explanation and but to read this part in a real life way and it mean he be the one who be sell dream manual and and sing be just like normal people who just buy one and then and make a dream . most importantly and the change age of adult sing and the deaf girl back to young kid at the end part give a huge hint that they still at their kid age throughout the movie . the butt boy and bucktooth jane and tailor and landlord etc show in the end also imply that they be not legendary guy in the movie and they be just normal people like u and me . all the story be a dream do by young sing . he have evil mind indeed and but he wish to be a good guy and he wish great power will happen to him so that can save at least his girlfriend and and then if possible and save the world . this be a dream not only for him and it be a dream for all movie fan and and also a dream for people in normal life . we go to theatre so we also have dream . this film be positive and because it give u many implication . one of them be represent there be many way to make a dream . don not know how . here be one .