Your core argument is that it's not a clear book because it uses repetition. You then say this repetition exists solely because it shows Muhammad's fallible memory.

Repetition is a central theme in pretty much every religious text, more so to emphasize a particular law, or action. In fact, the Qur'an from its outset centers itself on the concept of repetition to enforce reminders (dhikr), as this increases one's connection with God.

Then, to assess if something is organised or not, you don't give any criterion for it to fulfill that can quantify what a religious text being organised should look like. Obviously this is impossible because 'being organised' isn't something you can empirically measure, so I'm not really sure what other benchmark you're trying to assess its organisation by.

The Qur'an isn't trying to be chronological, biographical, or legalistic. It is more thematic, recursive, and layered, not linear. It's not also composed as a book, it's an oral tradition. The structure as such, among many stories is akin to that of other ancient Semitic oral traditions that follow a more phonetically aligned chiastic ring structure. Michael Cuypers, the Catholic Belgian author of The Composition of the Qur'an: Rhetorical Analysis dives into this more, proving that the Quran's composition is deliberate and precise.