Is true aggression common among puppies? No, it’s definitely not and what you’re worrying about is most likely not deep-rooted aggression.
Your puppy may act aggressive all of a sudden as he undergoes different mental stages which can include a fear period, puppy biting, and phases of testing boundaries or discovering rough play.
The most common signs why owners deem their puppies aggressive include biting, chasing, jumping, but also more serious behaviors like snarling or snapping at the owner or other dogs.
Biting can be due to teething, chasing you can signal play, jumping might mean your puppy wants you to interact. However, you’ll want to teach your dog to contain themselves and be disciplined about how far they go.