Why do dogs bite people?

It's part of their language. When we dont listen to the warnings, when they get over stressed and we don't help them the only other thing they can do is bite in defense. They don't know our rules or language. If we have been warned multiple times by a dog and ignore it, decide not to listen etc they simply do a quick bite - we don't have the fur and thick skin to protect us from the bite. It can be anything from a warning nip to a down right attack if they are feeling overly frightened.

Their bite is their warning system, their defense system, dominance system and protective state depending on where, when, who, what and why.

There are multiple reasons why dogs bite.

Aggression

Fear

Annoyed

Self defense if threatened

Going through the puppy biting phase

Play biting

Dogs do not naturally consider people their food. Even predators much stronger than dogs learned YEARS ago that humans are not their prey.

But, people still use that prey drive to TRAIN their dogs to bite people.

A dog not trained to bite may still bite a human out of fear aggression, to fight to protect its territory, or to defend itself and its pack including human(s).

And, there are those accidental, unintentional bites or play bites & puppy bites.

Usually, out of self defense, because they are afraid or due to their bite reflex which can make a dog bite in reaction to fast movements around their heads and other things. They don't think we are food or they would eat us.

Well technically its a reflex so they just do it when they ffeel threatened or bothered

Sometimes because they are scared, Dominic.

No. They do it out of fear or to protect their territory or out of aggression.

because they dog like the person they bit

Untrained and unsocialized.