Yeah our boy is not aggressive but it's more he watches and is extremely alert to the kids my youngest flee over he bolted to him crying my puppy started crying and licking him just sat beside him .Lots of people don't believe "protective" behavior in a puppy can happen before 12-18 months. But I've been around awhile, and I can see it manifest in pretty young puppies.
My own dog, and you can check there were some spirited debates here on this forum about her protective nature early on, but she's grown into that now...at 4 yrs. She's awesome!
Not overly aggressive, and maybe doesn't have the fight in her that some people want, I don't know, and don't care to test and/or bring that out.
But she's definitely protective still...
My Vet Runs our german Shepherd club obedience classes , and trains dogs for show same thing said as early as 12 weeks it can be seen .