Chronicles of Gaia
OR: Why are PCs so much more powerful than most townfolk?
Before the dawning of the 1st Era, all the races of men were roughly as powerful as 20th level characters.
When the Deus left the face of Gaia, however, ascending to the heavens and descending to the hells, most of the new offspring of men and corrupted were far more frail, weak, and slow to learn than their parents. At first causing great alarm, people soon realized the truth; most people were born with new souls, which would rarely grow in strength, while a precious few were born with the souls of the First Men.
These precious few are known as the Reborn. By the time they reach the age of majority, they already exhibit greater capabilities than Mundanes or New Souls. As they progress in their lives, however, the gods and devils reward their activities by strengthening their souls, enabling them to rapidly grow in capabilities and becoming harder and harder to kill.
Today, the Reborn constitute roughly 1% of the population. This makes them rare enough to be notable and special, but not so rare that they are surprising to encounter.
For a real world reference, roughly 1% of the US population is in the Armed Forces. Think about the people you know and interact with – most of them are not in the military, but it’s not a particularly surprising or noteworthy event when you see or meet someone who is.
In game, the favor of the gods (and devils) which leads to the bolstering of your reborn soul is represented in experience points. The thresholds at which you advance in level represent the point at which your soul has grown to the point that you become tougher (more hit points) and can learn new abilities (class features) and/or grow in your general capabilities (proficiency bonus).
This is why a young PC – who is a reborn – might be able to have comparable smithing skills to the town smith who has been working his or her craft for decades, or out fight a new soul soldier who has trained for years longer than the PC.