I suspect that folks were eating horses long before they were riding them or using them for draft animals.
I have read a theory that the Americas had large herds of horses long before Europe found us. All horses long gone for hundreds of years before the horse was brought back to the Continent with riders on their backs.
Some say the horses were killed for food, society's at that time were hunter gatherers and few took the time to stay in one place and tame anything for their benefit. Wolves were not tamed or any idea of the dog except in the far north to help the Eskimo.
Birds of pray were not taught to be trained to catch pray So as I was told by an American Indian years ago, the society for hundreds of years kept on the move eating what they could find and never thought of taking a food source and using it for anything but food.
When Europe arrived they brought things the natives could not understand, they brought Dogs that worked for them, horses that humans rode upon, milk cows and these small cats to keep down the vermin in a settled town. Mules , oxen and donkeys that the invaders did not eat but used for their benefit.
Then the very idea that these strangers would want to stay in one place and not move about as they did must have been a mind bender for the society that had no idea what these strangers were doing and why.
Didn't take but less then 10 years for the indigenous to figure this out. Copy the ways of the invaders, steal a horse not to eat but to ride, dogs not to eat but to give a warning of enemy about. First milk cows came here in the 1700's and I would guess sheep and goats earlier.
Early technology as it was, in animal husbandry and agriculture, the arts and science of unknown people, the gun with the first knowledge of the Chinese that that were a world away.
The Indigenous people never had a chance to go from eating horses to riding on them.------Culture, their religion and tradition .
So I would like to know about the very first man of America indigenous society that decided to do the impossible, to jump on the back of a horse and run with the wind. A feat as big as those that went to the moon, -----History changing.