As you describe the situation the dog seems to be quite "normal" (no history of mistreatment) and some shyness can be expected.
First I have two remarks:
This is not about dominance, or the dog wanting to disobey you, trying to control you or whatever. These kinds of "explanations" lead nowhere, are often counterproductive and sometimes lead people to actually mistreat their dogs ("asserting dominance", "alpha roll", etc.). A dog that seems to disobey on purpose can be very frustrating, but keep in mind that he's not doing that to piss you off, even if frustrated it is your role to teach/train him so that he'll succeed.
Dogs can have a single bad experience and remember it very well. Even if your dog was treated very kindly by the breeder, maybe it had some bad experience and that's why he's afraid of you. E.g. someone with a big beard and a red hat stepped on his tail, and then he's afraid of people with beard and red hats...
So the dog is shy, what do we do?
Using positive reinforcement and marker (clicker) training, you can make some good progress.
So the goal is to teach the dog that being around you is a good thing. To do that you have to reinforce every tiny steps he can take to come closer to you, to go out when you're at the door, etc.
So you idea of using treats is a good one, but you have to do it differently: if you hold the treat in your hand and he's coming to you, that's a good step you'd like to reinforce, but if you have the treat in your hand, you can only reinforce when he's coming very close to you. So that's like a binary situation: either is very close to you or he's not.
The key is to reinforce every tiny step: take some treats, as he's approaching "click" and throw a treat. That way you reinforced him to come to you, and at the same time you hit the "reset" button: he's going away to take the treat, so he can come back and get another treat ! That's very powerful in term of reinforcement.
At first you can show him the treat to motive him to come closer to you (lure), but then do it without the treat, it is a reward, not a lure, coming when he's offering the behaviour.
As time passes, you'll only reinforce him when getting closer and closer to you. Another thing to keep in mind is: don't just make it harder and harder, sometime you can reinforce an easy step, that makes it fun for him and easier for you.