Does "human aggression" mean aggression against humans or human-style aggression?
Sorry, unprovoked aggression against humans. Most dog bites don't happen "out of nowhere" - there's often quite a lot of dog behaviour warning signs that the people involved have ignored or not understood. Unfortunately, quite a lot of dog bites (particularly involving children) that have an underlying human cause (e.g. kids trying to ride the family dog and it biting them because it is in pain). "Human aggression" or "human-directed aggression" is used to describe aggressive behaviour against people that does not appear to have arisen from another stimulus.
While I agree with all of the above, I'd add that most dogs will deliver a warning nip first, usually not breaking skin.
Early this year my daughter visited with her son (2.5yrs old). He is used to dogs.
We have a middle-aged Border terrier (which were bred for hunting). Despite warnings, my grandson kept pulling the dog's tail and poking him. One time, they were out of sight (through a doorway) and there was a growl and a wail. Dog had delivered a warning nip and scarpered (no skin broken, very slight bruise).
We kept them apart.
Same grandson visited this year. He's learnt his lesson around dogs, and was more polite. Dog was very wary, but they accepted each other (I have some lovely photos of them sitting together on the rug).
Some dogs, and more common in some breeds, go from nothing to full-on attack.
They aren't suitable for any use or habitation and in my mind are 'dangerous dogs'. Keep them muzzled at all times or have them put down.