Could you post a side-profile photo? It almost looks like he's a Light-Brown Dutch Bantam (like one of the birds in my avatar) or some sort of Old English Game Bantam. Looks about 4-6 months of age, though he could be younger--bantams mature rather quickly. It can take a while for roosters to develop spurs; mine only get obvious ones when they are 6-9 months of age. He's a very pretty boy!
As for why he doesn't like jumping, that is odd; most bantams of his breed are great fliers. Do you think he can he see all right? Maybe he's just afraid of jumping--chickens can be fearful of many different things, and sometimes for no reason. And, at least in my experience, male chickens are awful at jumping down, especially the bantams. They just drop to the floor without even flapping their wings. Its a wonder they don't break their legs!