The Native Americans -as they are called ,actually crossed the land bridge between Asia and Alaska during the last Ice Age. They slaughtered the Mammoth ,Camel ,Horse ,and other large beasts for food. Why did they not domesticate the Buffalo?
Actually, there is no proof they "slaughtered" all those animals other than any other groups had. Remember, almost all the megafauna globally died globally, not just in North America.
And no, the buffalo was not really able to be domesticated. They are simply too large and too poorly tempered for domestication. And a great deal of that is actually genetic.
We now know that there is actually a genetic aspect of domestication. And all of the animals we have domesticated (dogs, goats, cattle, pigs, etc) have genetic differences between them and other wild animals we have never been able to domesticate (American Bison, deer zebras, lions, etc). Even the cattle we now eat are a hybrid with cattle that did have that mutation (water buffalo) with one that did not (auroch). That is what injected the required genes into their bloodline that let prehistoric humans finally domesticate them.
There was no such animal at all in the Americas to breed the bison with to allow that to happen.
That is what you seem to be missing. In every single instance of human domestication, we started with a mutant that had a mutation that allowed it to de domesticated. We then propagated that mutation by breeding it with other closely related species. None of the "barnyard animals" we know of today is actually "natural". They are the result of using a mutation to our own advantage. And without that mutation, nothing can be domesticated.
And eating for food is nowhere near the same as domestication. But notice, there is a reason why nobody ever domesticated the Bison, either in Europe, Asia, or North America. The same reason the zebra has never been domesticated. Genetically, they simply lack the genes to be domesticated unless they can be crossed with anther animal that actually has the appropriate genetic mutation that allows for domestication. The closest is some that have been crossbred, like the "Beefalo".
While that looks like an American Bison, it is not. It is a cross between farm cattle and the buffalo. And those indeed are domesticated, because of the genes they got from their cattle ancestors. Genes completely lacking in the Buffalo side.
Might as well ask why the Indians never domesticated the Bobcat, the Big Horn Sheep, or the Antelope.
There have been many experiments in recent decades in domestication. One of the most well known out of the Soviet Union that started over 7 decades ago. And it has indeed shown that the members of the group that were domesticated all had mutations that allowed that to happen. But as it was a canine, the genes involved were already present but simply not always active.
Animals like bison and zebras do not even hate those genes as a recessive, so could not be domesticated short of interbreeding with another that does.