Regarding safety, in most of the journals that I have read people get injured or sick and have to get to the nearest town. Sometimes that is more difficult than anticipated.

As for being attacked by a human, I have a theory on that.
There are a certain percent of crazy people in the world, so your likelihood of running into one is dependent on the number of people around. There's always one around somewhere. You just have to learn to avoid them.

Word travels on the trail pretty fast too so you get an idea of who to avoid. Most folks travel in groups. They're not really together but have a similar pace and end up generally at the same campsites in the evenings. So, if there is a problem there is usually people around to help.

Hope that helps.