The domestication of horses behavior changed quite a lot because before they were domesticated they were WILD horses. So they probably were aggressive animals. Considering how big horses are they definitely would have kicked you if you approached them. Since horses have been domesticated they act less hostile. They have also became smarter, they have a really strong fight or flight system.
(I don't know if this helped, but it took me awhile to find this information)
They are
Clever
Generous
Sly
