How did Shinto's religion begin?

How did Shinto's religion begin?

Many polytheistic religions have no clear beginning.

it began as a folk religion in which every tribe had a specific Jami (ancestor or spirit) that they worshiped

I am not sure I entirely understand your question, but to answer you the best I can, to my understanding, no one really knows when Shinto began. It has no written "gospels" and is a philosophy and a way of life that goes back before Christianity. Since there are no writings, there is no way to date it.

I would normally post some info here along with the link, but it's a little long. Anyways, here's the link! Hope it helps you!

Shinto is the native and indigenous religion of Japan and up until the second world war it was Japans State religion. Shinto practise is a form of animism, believing that natural objects such as rocks, rivers and mountains have gods/ spirits associated with them. Shinto shrines are often placed on auspicious mountains or rocks to designate their sacred nature.

ancestor worship is also a key practise in Shinto.

Being the indigenous religion it would be hard to pinpoint a definite starting point. it is more likely that the religion evolved over hundreds or thousands of years into its current form. it is still changing as some Prue war beliefs and practices have been drooped. Shito is as much a philosophy and a way of life as it is a religion.

I hope this has helped,

Kindest regards,
Paul...

The earliest origins of Shinto are lost to history, but it seems to have been established by the late Jomon period. Most likely, after the arrival of the earliest ancestors of today's Japanese, each tribe and area had its own collection of gods and rituals with no formal relationship between each of the areas. Following the ascend ency of the ancestors of today's Imperial family to a position of power among the other groups, their ancestral deities were given prominence over the deities of other groups, though different systems continued to coexist.