What was mental life like before the breakdown of the bicameral mind? We know what it's like afterward because each of us lives in a modern, post-breakdown mind. But before was very different.
In the bicameral mind, the two hemispheres had evolved into two very different beasts. As today, the left hemisphere was in charge of interacting with the world. It controlled the process of speech. It controlled the right hand, the hand that reaches out, the hand that tests the world, the hand that grasps, the hand that manipulates the pieces of the world. It is not clear what else the left brain did. What it didn't do was perceive or think about itself. Without a sense of self, the left brain was free to act much as it does today, but without regret. It probably was the source of the symbology (hieroglyphics) that are seen in the works of the ancient Egyptians, who lived before the breakdown.
As today, the right hemisphere perceived reality directly through the senses and lived in the flow of the world. It learned and kept all the knowledge of how to survive and prosper in whatever world it lived in. It knew where the stars reside in the sky. It knew the myriad plants in the surrounding natural world. It knew how to nurture growth in a garden or field and how to avoid predators. In fact, it seems much like our present right brain.
What was greatly different before the breakdown was how the hemispheres interacted. Remember that the corpus collosum, which is the primary connection between the cortexes of the two hemispheres, is relatively small compared to the things it is connecting. Jaynes proposed that the primary communication crossing the corpus collosum before the breakdown was words. He found that the area of the right brain corresponding to Broca's area (the left brain's speech center) is also capable of speech even though it is not connected to the vocal centers.
Jaynes proposed that the right brain literally spoke to the left brain. The left brain perceived this speech as coming from outside of the body and deemed the speech to be coming from a god or gods. The content of the speech was largely imperative: do this, do that, don't do the other thing. The left brain listened and obeyed. Without a sense of self or ego, there was no resentment against the voice. Moreover, the voice was generally right, meaning that what it said to do needed to be done for a good reason: planting, making offerings, and otherwise contributing to the community.
As today, the right brains of a community were closely integrated with one another. Mostly, all the right brains in a community saw things the same way, so they behaved as something like a "hive mind", with each right brain directing its left counterpart to perform the actions which would benefit the hive. Conflict among the members of a hive was uncommon since there was a shared vision and no egos to get in the way.
This is not to say there was no conflict. Geographically separated hives were not likely to share the same sensibilities, so when they came into proximity they might fight or otherwise act out their differences.
Life before the breakdown wasn't idyllic: survival has always been hard. But people didn't feel sorry for themselves or resentful. Nobody was taking advantage of others, so if a group suffered, it suffered together. When there was bounty, as during early Babylonian and Egyptian civilizations before the breakdown, people naturally organized themselves in to efficient hierarchical civilizations, with right-brain communication holding each level of the hierarchy together and connected to its leaders. Jaynes proposed that the voice a person heard sounded like the voice of the leader in the hierarchy. An ordinary person didn't separate that from the voice of the god that person represented.
The pyramids of Egypt were built well before the breakdown, and none were built after. The mystery of how the pyramids were built makes more sense to me as a product of a hive mind living in a bounteous time than any other explanation I have heard. We know the pyramid builders were not slaves, and they showed an amazing amount of organization over an extended time.