Because it was easier than inventing the scientific method

@A2Jennifer one answer

Buy what was happening in their lives to require it.

No it is the 'how' that is important. What happen was that people evolved/invented language, and that gave them a vast new capacity to lie, far beyond anything they had ever had before. And because language and its side effects were new things, old biological evolution had given us no tools to deal with it or its side effects. So that people had no bag in which to put the new lies and keep them safe, in consequence some of them started to run around wild, doing all sorts of damage and harm. But the reason why the lies were created in the first place hardly matters, because they could have been created for totally trivial reasons, the lies moved on and got so far from their starting points, the reasons they existed in the first place became irrelevant.

@Fernapple On most occasions I am with you but on this issue I would argue for something more than deceit.

As an eventual by product yes but not as a cosmological narrative, and many of these disparate narratives have a kernel of similarity.

In the first instance I would advocate for a collective psychic need to understand the mystery of life.