You have a very normal puppy.... somewhat timid.
Look, I'll tell you first up, forget everything you have heard about needing to dominate your puppy. You are scaring the poo out of him. Locking eyes with him is a very intimidating thing to do.
Think of your puppy as a baby dog, not some sort of mysterious creature. He is much like a 2 year old child. Your mantra should be "would I treat my toddler like this?" if the answer is no, then don't do it to your puppy.
He is new to your home, alone and afraid, and now his human is doing frightening things to him.
Keep in mind a puppy is very orally oriented, just like a baby, so most of his chewing and mouthing is simply that same baby behavior.
Get yourself a couple of books so you don't ruin this puppy. If you continue to frighten him, he will grow up an aggressive fearful dog.
ALWAYS be gentle and non-scary to your puppy.
Talk nicely to him.
Make sure any time you touch him it is pleasant for him.
Do not shout at him or yank him by the leash.
He is a baby. Treat him as such.
Get some books.
Read some threads in the puppy section on this forum.
Don't watch Cesar Milan.
Don't listen to the dominance talk... you will ruin the pup.
You need a crash course on puppy raising. It actually is not that easy, nor is it intuitive, and mostly the advice you get in popular culture is old fashioned and harmful. It's the equivalent of old advice that you must punish your children with a switch or belt. We know that not to be true now for human children. Same thing for puppies.