Indians are humans -- their individual and tribal selfishness would have overwhelmed their considerations of the animals being sacred and they would have exploited their commons. Even without white Americans involved beyond being a source of rifles and ammo, the Indians would have hunted the buffalo (for food, lodging, clothes, tools and furniture) until there were too few buffalo to support them. That is the all too common population boom during followed by a crash after they decimate their prey.
That's not true in general. They were more, or less aware of the problems with the commons and took care to farm and use their resources wisely. The fact that they noted the problems caused by the widespread slaughter of the buffalo proves that.
Minus white civilizatin produced weapons, the Indians couldn’t kill off all the buffalo, even when they drove entire herds over cliffs.
All that accomplished was a large feast, followed by lots of labor drying meat and prepping hides.
Then, it was a 25 year wait until the next herd grew up.