Just heard a talk on the symbology of Matsyavatara. It turns out that in the earlier times people would predominantly hunt for their sustenance. Now hunting in the wild has two difficulties. One, it takes away most of the time and energy. Two, its unsafe - quite possible that humans become prey to animals.
Manu, the ancient law giver, saw the difficulty in this and sought a way out. He started gathering people towards the sea coast. Fishes were abundant in sea and river, and there wasnt the threat of getting hunted in return either. So people had more time at their dispense, which were used in discussing higher philosophical matters at hand. This lead to rise of Brahmanas, who were proficient in such dwelling on the greater truths of life. Kshatriyas were needed for the protection of society from animals. Vaishyas and Shudras were necessary for sustaining agriculture. No community is superior, and none inferior - its just a division of labor...
