My mare "protects" me to a fault. She is a ham, and loves people to watch her do her thing - but she does not want man or beast to come physically between us - especially at liberty. She is well behaved on a lead if I hand her to someone and walk off (if I just stand there, same thing, she doesn't want the person between us), and she will try hard to keep tabs on my whereabouts.
I play a game with her sometimes just for kicks - if she walks off I will fall to my knees and double over and act like I am dying (I did this once w/o knowing DH was about, and he came running to see what was the "matter"
) - she will always come carefully stand right by me. I did an experiment one time after I slipped, fell and hit my head on a rail which really smarted. I was holding an open container full of her RB and, thinking on my feet, while I was still down I acted like I was knocked out to see if she would just eat the food and pay poor me no never mind. :) She gained a lot of brownie points that day, because she never went for the food, she just kept gently smelled my face, arms, what not. Mind you, I trust her w my life, there are few horses I would try this with....I knew that if she chose to eat the food she would be careful of me.
Do I think some will protect you - absolutely. And, some will "protect" other creatures. My old buckskin loved to have a "pet". He was always head of the herd - no matter what size the herd. I always figured having a pet to him was like a "status" thing. He did not
like dogs and was very aggressive toward strange dogs, so it was interesting to watch him protect our dogs to the teeth and let them hang w him. Then one regretable day, we got a goat (ugh). The goat was the devil himself in disguise, but sure enough...the buckskin decided she was his pet. The goat would harass the other horses, and if when they had enough and went for the little demon it would holler - the buckskin would smoke a trail
from far off to come protect it. He actually let the little horror eat with him when no other horse in its right mind would go close to his food. So yeah, I think they will protect "others"....sometimes people, sometimes other animals.