Good story. I truly believe alot of mysterious sightings of abnormal creatures are explainable, just as the conditions of weather, light and perception caused such alarm for you and your brother. If you had run away instead of investigating the incident, you would have truly thought you had seen a ghost.
I have been born and raised here in the higher elevations of WV, in the twin towns of Davis and Thomas, just outside of Blackwaterfalls and Canaan Valley State parks. On some Bigfoot sites, there are as many as four sightings of the sasquatch reported here in my hometown area. These sightings are by people who visited, or were hunting, and not native to our area. Trust me, I am 55 years old, and I and my friends have lived in the woods since childhood, and no one who lives here has ever seen a bigfoot.
I don't know what these "visitors" imagined they saw, but we have an abundance of bear, some mountain lions, bald eagles, fishers, and beaver, all of which could fool the novice in the woods in the right conditions.