How much mental stimulation/exercise is he getting? He's still a baby and sleeps a lot, but think of them as young toddlers- when they're tired, they act out. When they're bored, they act out. When they want something, they act out. They lack impulse control and explore the world with their mouths, so biting you is FUN!
Unfortunately the biting is one thing this breed is very known for (they aren't called landsharks for nothing). It's not an instant fix... it's a phase. It's a long one, but patience and consistency with redirecting are the keys. At this age, your puppy really doesn't understand what "no" means, especially not in this context. Up the level of controlled interaction- they demand attention with their mouths. If they're over-tired, they'll get extremely mouthy... nap time in the crate is your best friend.