Here's a thought for all to ponder.
Horses have been on this planet as long and some say longer than us humans. They have a discernible social structure and language. It is the human who demands that the horse adapt to what the human wants. Separation from the herd, loss of comfort and safety that the herd provides, when to eat, when to sleep, when--and who- to breed, how to interact, how to think, etc. One might say that the human wants the horse to become more human so that the human can apply its language and thought process to the horse.
I can say that I cannot train a human horse. I can train a horse who has the experiences of a horse. So the first step is always undoing the human part of the human/horse to get to the horse and then train from there.
For those who think they can train a human/horse all I can say is good luck.