Answer:
I can move even when you are still. I can be one or many.
Be sure to shout for its answers are weak, but there is no language it cannot speak.
In buckles or lace, they help set the pace. The farther you go, the thinner they grow.
What looks back but cannot see?
As I walked along the path I saw something with four fingers and one thumb, but it was not flesh, fish, bone or fowl.
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?