The biggest problem I see is with the premise of trying to investigate the nature of the human mind in antiquity by examining a few scraps of literature. Even

The biggest problem I see is with the premise of trying to investigate the nature of the human mind in antiquity by examining a few scraps of literature. Even if we accept the premise of bicameral minds existing and these pieces of literature being written by such people, I think that tells us jack shit about the nature of the average human 3000 years ago. There's no reason to think these authors were representative of the average person in their age. These writers might have been on the autism spectrum, or had schizophrenia, or any number of other unusual mental traits that could give their literature unique quirks. It's like reading a bunch of literature from the European middle ages written by monks, and then concluding that most people back then were celibate men. The social and cultural circumstances of an age leave a mark on what sort of literature is created and preserved.