Born In The Sun?

Riddle: I am very important to all living creatures. I was firstborn in the sun. I am a chapter in textbooks and I am not made of fire. I make the sun-worthy. Too much of me may kill you. But humans can still prevent me. What am I?

Answer: Heat!

Source: https://www.riddles.com/10419

I am very important to all living creatures. I was firstborn in the sun. I am a chapter in textbooks and I am not made of fire. I make the sun-worthy. Too much of me may kill you. But humans can still prevent me. What am I? — Born in the sun? by SarvRiddles 235 v1.

Riddle: I am very important to all living creatures. I was firstborn in the sun. I am a chapter in textbooks and I am not made of fire. I make the sun-worthy. Too much of me may kill you. But humans can still prevent me. What am I? Answer: Heat! — by SarvRiddles 235 v2.