My home campaign is a new world created for mortals by Gods, many of which who were once adventurers themselves. Mortal souls can be enriched with power and accomplishment, and earn greater rewards in the afterlife, and the new world itself is a crucible for people to seek their passions and build their own legends. Many Gods and other Entities create and utilize Dungeons as tests, for the full spectrum of aligned perspectives. There are some known dungeons, but far more have not been found yet. Much of the world is still being explored. It's a world of exploration, adventure, puzzles, challenges, and accomplishment.
Even the bad guys know this. Everyone knows good, evil, order, chaos, and balance is real, and that there are evil monsters, as well as entities and people who choose an evil path, because the Lower Planes aren't technically a punishment. They include rewards for being evil. There are factions and organizations that embrace the full spectrum of ideals, so there is a lot of potential for conflict and challenge.
Adventurers are people who actually embrace that lifestyle. On the other side of the spectrum, some people who can't handle the stresses of an adventurous life stay to the safer realms and try their best to be the best they can with their passions. Some faithful crafters even sacrifice their high-quality creations to their Gods, and those creations may appear in dungeons or other treasure hoards, and become sought after treasures. Everyone has a way to build their own legend, whether locally (like cultivating the best green honey in Honeyhome) or globally (like an archmage who earned the Staff of Power from the Diamond Plinth of Power dungeon). The Archmage just might get hunted/challenged by rivals/monsters who want that treasure for themselves.