Hi.
your pup is young, so regardless of lines I think it is a great thing that he loves everyone...many dog owners would love to have a dog that loves everyone
As far as development and acting aloof, I personally think it depends on the dog. There isnt much that I have heard where it is a difference of lines that makes a dog more aloof than another, just the dog itself, or experiences in the life of the dog.
This is my experience: We have 2 german shepherds right now that are around the 1 1/2 yr old mark. One is a working line male, the other is a rescue female that in my best guess is german or a mix of lines. They love everyone, they seem to think life is their playground
. While it can be hard to teach them not to jump and kiss everyone, I still like it that they love to be with people.
My husband, and eventually myself, had an american line gsd since she was a pup (I met her when she was 4), and while she was more mellow she was much more aloof, from a younger age. I do not equate aloof with protective. She was still very much a love people dog, just more aloof.
So I would certaintly not think your dog is a coward, in fact he sounds well socialized.
I wouldnt worry about him protecting you...he is a pup have fun with him
I personally don't look to either of ours for protection, more comfort and a deterrent at best!!