Civil Aggression in German Shepherds
Civil aggression is the dog's inherent level of suspicion towards humans. This is what makes socialization the most important thing a family owner can do for their dog. If you raise a pup to be around people all the time they become more people friendly as long as their experience with those people are positive ones.
This socialization process will alleviate most of your concerns about inappropriate aggression towards humans when the dog becomes a full adult. This helps the dog to understand the difference between real and perceived threats.