My Clone Is a Demon Boss

A thousand years ago, he was a demon boss, and a thousand years later, he was just a righteous little guy who had just entered the path of immortality. The young people of the earth traveled between the worlds of a thousand years ago and a thousand years later on this fairy continent. Some random small changes changed the history of the thousand years. Did they change the history? Or is this history! Constantly relying on the foundation left thousands of years ago, step by step towards the top.