Answer:
It goes up and down the stairs without moving.
What is used by man, tossed by trees, everywhere but unseen?
What Can Fly Without Wings
I am the first you ever saw, what greets you every morning and what goes out in the end.
If you are to keep it, you must first give it to me. What is it?
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.