Shinto: An Indigenous Religion

Even though, people did consider Shinto as an indigenous religion mainly due to the human relationship with nature. It is still unclear and confusing as to when it became a unified religion or even where it got its start. As you said, these beliefs are indeed as old as Japan itself. Before Buddhism and Confucianism migrated to Japan, the beliefs that were already well ingrained in Japans culture and did not even have a name. Previously to being grouped into one religion, these theologies were not even considered a single faith. Shinto to me just seems to be a convenient label that they decided to give to the different faiths found in Japan. The beliefs that are now known as Shinto was indeed greatly altered due to Buddhism and Confucianism.