He's a puppy, even if his breed makes him a big dog. The trouble for big dogs is that at six months they're pretty big in size, but they're still puppies. Puppies aren't as sure of themselves as grown-up dogs are. They can be skittish. Dogs have those sensitive ears, so noises may get his attention more than it seems they should.
I don't think it's possible for anyone to really know how extreme your puppy's "issue" is, but unless it's extreme he's probably fine. There are some households and people who may contribute to a dog's feeling particularly skittish, and if you have people around who aren't very sensitive to his need to feel safe and calm they could be contributing. If someone expects too much of him in terms of behavior it could make him "frazzled". If there's anyone who yells at him that can make a dog (especially one so young) frazzled.
Also, dogs are like people. They have their own personalities. Some may be more nervous about some things at six months old than others. Some that come from a shelter have had some emotional upsets (and worse) that can affect their sense of sureness too.
I'd say just make sure he feels safe and secure. He can be told "the rules of the house" without yelling or making him feel frazzled. Treat with with lots of kindness and love, but make sure he knows you're a stable, in-charge, kind, "friend" capable of helping him feel safe. Most of the time there's a reason dogs are afraid of people, but if they are made to feel secure and loved they'll calm down and learn to trust people. (Something else is that if he's had a bad experience with having his nail clipped he may have learned to be afraid of the sound of clippers.)