[Jaydedlifestyle12]

The way I see religion is like this:
(I'll use Christianity since it's the obvious one)
Pretty much every story told by the bible was told generations before hand, and adapted. We know this because of writings that date back further than the time of Jesus.
People thousands of years ago were a lot simpler, so these stories were easier to explain and tell, and they stood the test of time.
Jesus was real, we know this, was he the son of God? Highly unlikely. He wasn't as pure as the bible depicts him, there are many accounts written within the bible itself saying how Jesus whipped those who disagreed with him and how he destroyed property. He endorsed domestic violence, and slavery. He sounds as human as anyone from that period.
It's likely that he was somewhat nicer than people, and got recognized for this, making people hail him as the son of god (seeing as they were simpler and probably easier to manipulate).

So, in the end I think it started because people were delusional about it, and passed it through their families which spread outwards and everything continued from there.