When, following the cataclysm, the first groups of humans started emerge from their hiding places, they were not the same people as those who had fled from the violence of the Gods many generations ago.
With the loss of the ancient cultures, technology levels had decreased and much knowledge had been lost. The old languages, teachings and mythologies of their ancestors had been diligently passed on, but inevitable changes had been made, and much was forgotten.
Humanity had to rebuild entirely. However, humanity is resilient, and not everything had been lost. They planted their crops, farmed their animals, and re-created their societies and city states at an explosive rate. Soon, humanity worked its way back up to advanced civilisations.