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As you haven't had him long & are still taming him it might be better if it was just you that handled him until he's more comfortable with it, it might be a bit much for him to be getting used to more people in the early stages of taming.
Are you handling him in or out of the cage when he bites? It's better to buy or make a large enough playpen so you can sit in with him, let him get used to climbing onto you & your hands before trying to just hold him, it's only natural for young hams to want to run around & explore rather than sit still so don't expect him to sit in your hands for long just yet!
If he's in a playpen or other safe area then jumping isn't really a problem as long as you keep him close to the ground when you interact with him.
Sometimes biting or nibbling is just a way of exploring, washing your hands with unscented soap before handling him should help.