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Horses allowed early people to hunt for faster prey, to wander farther than before and to create much bigger farms due to pulling plows.

The notion that horses had something to do with the evolution of humans is idiotic.

Horse riding didn't start till at the earliest 4000 BC or so, long after modern humans were fully developed. Early horses were too small to carry a full grown man for long.

Early horses could not pull heavy loads such as a large wagon or a plow. The harnesses used choked the horse, so for such purposes oxen were used instead.

Efficient horse harness for draft purposes evolved in China from about 1 AD to 500 and didn't reach Europe till about 1000.

And horses for use in plowing didn't take off in Europe till early modern times, when the Chinese (again) invention of the moldboard plow finally got there. It allowed a single horse to pull (using the collar harness) a plow.

Previous plowing methods in the heavy soils of north Europe required teams of multiple oxen, which necessitated the manorial or communal organization of farming.