thank you for saving him
He sounds like he is really bonded to you, the biting, sounds like he's 'mouthing' you, (harder than you'd like but he probably doesn't realize it's hurting you)
And it could be an 'affection' thing, since it's not aggressive..My thoughts are, he just doesn't know it's hurting you and doesn't know it's not really acceptable.
With that, does he like toys??playing tuggie games?? Get a good tug toy, when he goes to mouth you, start playing with him with a toy..OR, if he's food motivated, keep treats on you (YUMMY high value treats!) when he puts his mouth on you, work on him to "leave it', as soon as his mouth comes off you, treat him//good boy!
We insist on pictures of your new boy!!