Dogs hump for many reasons, not just to assert dominance. They learn it is fun and it feels good, simple. Many do it when they get excited and as a form of play. My dog has certain playmate dogs that they take turns in humping each other in the middle of play, both friendly, get along, very submissive dogs. It's just play to them. They usually don't even do it right. Other dogs don't take kindly to it and tell them pretty much off the bat. No problem, they don't do it anymore. Now, humping me or my kids NO WAY. I don't take kindly to it, so again, he doesn't do it to me. He'll learn what is acceptable to you and what is not. Redirect him if you don't want him doing it to his toys. (You do have to consider having visitors at the house every now and then. Do you want them watching that?) Teach it is a no people thing to do by withholding attention and removing yourself from him. Notice I said removing yourself. If you use your hands and remove him from you, you are providing positive reinforcement to the behavior by touching him. As far as dogs go, with supervision to make sure things don't escalate, let the dogs work it out.
