This isn't a great story, to be quite honest. The story focuses less on the ways man used to start fires and more on the ways that nature started fires independently of humans.
That being said, it would seem as though the author is trying to express the fragility of fire early on, and it does seem as though he/she is saying that early on, humans just found a small amount of fire from a really dangerous origin to use as a kindling.
For sure, your answer should come from the second paragraph, which is the paragraph describing early kindling methods.
