What exactly was the soul? Everyone had their own opinion, but it was likely that nobody's opinion was close to the truth.
That was because there was no standard answer on what the soul was to begin with.
Creator Goddess Eich had never designed the soul in the first place. Souls had managed to come into existence by themselves. It was just that different researchers would analyze the soul from different angles.
Back in my original world of Earth, in Chinese Daoism, there was a belief that humans had three celestial and seven earthly souls.
The three celestial souls were heaven, earth, and human. These three souls had completely different functions, respectively being a human's self-consciousness, honor and the sense of shame, and lifespan.
My interpretation was the three celestial souls represented self-recognition, personal values, and the lifespan of your soul. These would form the basic hardware of any soul, and typically were fixed conditions.