Regarding Luis Michel who proceeded as far as Edinburg, VA in 1706 and did not see any Native Americans, he was about 50 miles south of the Cross Junction Shawnee settlement. He would have needed Superman's telescopic vision to see that far to say there were no Shawnee there. Moorefield, WV, where another Shawnee settlement existed, is over 60 miles away because a mountain blocks a straight path to it from Edinburg. Luis Michel would have needed both telescopic vision AND x-ray vision to see that settlement from Edinburg. As far as the Shawnee settlement on the North River, whether or not Luis Michel would have been able to tell if that was there or not would depend entirely upon which branch of the Shenandoah he followed North, as the North River, the South River, and the Middle River which all combine to form the Shenandoah.

Regarding Thomas Walker who saw no Indians in his 1750 expedition through southwestern Virginia, the Shawnee settlements I wrote of existed in the northern Virginia, not southwestern. And I doubt very much that Thomas Walker explored every part of southwestern Virginia. There are a lot of mountains there, and at that time they would have been well-forested. It would have been impossible for Thomas Walker to explore all of that on foot or even horseback in just one expedition, even if said expedition lasted for a number of years. You couldn't even completely explore the entire southwestern Virginia in a modern SUV in a few years.

The Native Americans were not so numerous by th 1750s in Virginia. The Shawnee themselves were never a very large group of Indians. You couldn't just walk any old direction and trip over them. Nor did they advertise their existence, given that most Native American tribes had Native American enemies at one time or another.

A Native American settlement or village can be anything from just a couple families on up. Given the low population density of Virginia at those times, it would have been quite easy to miss Native American settlements except for the large ones. Nor would any Native American necessarily have told a white man that he was from a settlement nearby, given the state of affairs between whites and Indians at that time.

The Cherokee stuck more to the Blue Ridge mountains for their settlements, from what I understand, with the majority of them living more in Georgia/Alabama and thereabouts.