I think that the view of the noble savage helped to subdue the Native Americans in the eyes of the Europeans and early colonists The image of the noble savage was applied to the Native Americans and rendered them into a position where they could not be seen as a formidable element to either respect or fear. This became instrumental in being able to subjugate them with relative ease:
For in the overpowering English literary tradition to which, even in their sanguinary cultural nationalism, they made obeisance, the Indian had been generally conceived as a noble savage, above and beyond the vices of civilized men, doomed to die in a kind of absolute, untouchable goodness; and American experience and understanding had been directed towards destroying just such a conception and replacing it with the conception of a savage in whom nobility was one with ignobility.
In this, an interesting paradox emerges. On one hand, the noble savage image is what enabled a brazen approach to be taken by the Americans and Europeans in moving into the new world in which Native Americans lived. Yet, once this interaction took place, there had to be a recasting of the noble savage as one who was "ignoble." In this, the noble savage image enabled Western powers and eventually colonists to overtake the Native Americans, with a redefinition evident once there was subjugation, in an attempt to justify said oppression. In this, the noble savage image played a vital role in shaping the thinking of the early Colonists and the Europeans both pre and post interaction with the indigenous people of North America.