Answer:
Runs smoother than any rhyme, loves to fall but cannot climb.
Used left or right, I get to travel over cobblestone or gravel. Used up, I vie for sweet success, used down, I cause men great duress.
What's a place you have left but didn't enter?
Bury deep, Pile on stones, My mind will always Dig up them bones
They have not flesh, nor feathers, nor scales, nor bone. Yet they have fingers and thumbs of their own. What are they?
What covers its face with its hands, speaks no language, yet most known what it's saying?