Answer:
Runs smoother than any rhyme, loves to fall but cannot climb!
Dies half its life. Lives the rest. Dances without music. Breathes without breath.
As soft as silk, as white as milk, as bitter as gall, a thick green wall, and a green coat covers me all.
I run through hills. I veer around mountains. I leap over rivers. And crawl through the forests. Step out your door to find me.
You saw me where I never was and where I could not be. And yet within that very place, my face you often see.
What covers its face with its hands, speaks no language, yet most known what it's saying?