For most of its life the lower scroll, and the Kojiki with it, was the second chronicle. The Nihon Shoki, completed in 720 in proper literary Chinese and organised by reign year, was the court's official history, lectured on formally and cited in ceremony. The Kojiki, in its awkward hybrid script and without dates, circulated far less. Its surviving manuscript tradition is thin, and the earliest complete copy is medieval.
Its elevation came late and came from scholarship. The kokugaku movement of the Edo period turned to the Kojiki precisely because its language was less Chinese, arguing that it preserved something native that the Nihon Shoki had dressed up. Motoori Norinaga spent decades on a commentary that had to reconstruct how the text should be read aloud before it could be interpreted at all, and that labour made the book legible to a wide readership for the first time in a thousand years.
What followed was more than literary. From the nineteenth century the mythology of the first scroll, transmitted through this reading, was put to work in the account of imperial descent taught in schools and enforced by the state, and after 1945 that use was dismantled. The book itself did not change. Shinto had no scripture, and the Kojiki was not written as one; it was made to serve as one, twice over, by readers with reasons of their own. Any account of it that starts from the assumption that it is a sacred text starts a thousand years late.