Were native Americans committing genocide against each other before the white man arrived?

No, they were not 'committing genocide' - they were fighting. So was the rest of the world.

I offer you the Crow Creek Massacre,,, which occurred about two hundred years before Europeans arrived in N. America.

https://en.wikipedia.org/wiki/Crow_Creek_massacre

Of course there were wars in North America , just as there were wars in Europe.  Christopher Columbus generally gets credit for the first expedition to reach North America, although there is a fair amount of evidence that Vikings were here much earlier

Of course. As a rule native American did not commit genocide (which is the deliberate and systematic extermination of a national, racial, political, or cultural group.Words mean things) but they fought wars and happily killed each other long before any white men arrived. The first recorded white men to arrive in North America were Norse explorers led Leif Erikson around the year 1000.

I think you need to look up the definition of "genocide".

Please note that killing your enemies in battle is not "genocide".

There is a difference between fighting and killing each other and committing genocide.
If you need that explaining to you anything more complex is just going to go way over your head.

Genocide means eradication or planned eradication of an entire nation, ethnic group or country. I know that Native American tribes were at war among themselves... but I never heard them escalating to genocide.

Yes, some even enslaving, and the Miami confederation, exterminating the Illini confederation at the siege of Starved Rock.

Gold Rush by non-natives !