Short who am I riddles

I am as big as you are, but I am weightless. Who am I?

I am the building with number stories. Find me who am I?

I am there when you are quiet. I am broken when you speak. Who am I?

I eat other animals. I have a big mouth. I am green. I live in the water. Who am I?

Slayer of regrets, old and new, sought by many, found by few. What am I?