I have been a form of currency I’m essential for life, but too much of me can lead to death

Now I am such a fun thing! I have so many uses, it's enough to make you sing I'm a dart, a start, and even a dash I can arrive in a flash, a clap of thunder to herald my arrival If you need lots of cloth or paper, you'll find plenty of me and I won't be a trifle I can be a gatekeeper, as long as you hold my key I can even help you fight or flee

In a line, they often sway, a moving dance, slow ballet. Gentle rhythm, side to side, tiny travelers on a glide.

A golden giant with a face that follows the light, standing tall in fields, turning its gaze towards the sky's warm embrace.

Change my first, and I’m a hardened substance that may have ancient insects or plants in it. Add a letter instead, and I become a person that belongs to a group. Make sure you throw water on me when you’re done. Smokey says only you can prevent forest fires!