I tend to emphasize attrition. The settlers just kept coming, with new waves of immigrants pushing on past the graves of the fallen, while the Indians could not replace their losses.
Prior to the Revolution, the British government tried to restrain the westward movement, but the settlers were gradually pushing inland anyhow. After the Revolution, the pace accelerated. The eastern woodland Indians were simply too thin on the ground to resist the spread of an agricultural population.
It is interesting to speculate on what might have happened if the disease wave had not decimated Indian numbers. The Indians who remained when the overland settlers showed up still practiced some agriculture, just not enough to support the numbers required to mount an effective resistance. Little Turtle and Tecumseh are probably the last two Indian leaders to mount a resistance that actually meant much. After them, it was just a long, bloody mop up operation.
European crowd diseases did the bulk of destruction against the Indian.
“It is interesting to speculate on what might have happened if the disease wave had not decimated Indian numbers.”
I’m currently reading “Guns, Germs and Steel” — which is an attempt to ‘get at’ why Eurpoeans and Asians came to dominate the globe. Much of it is due to higher population densities that resulted from a highly successful agricultural & herding economy. This resulted in many widespread human diseases, and a higher degree of immunity to same. So when European explorers set foot in the Americas, that first contact started waves of epidemics that decimated native populations, but not the reverse. This left the Americas wide open to colonization.