Your First D&D campaign
Glynn is a world much like any other, made mostly of water, and has numerous continents and varied cultures. The current competing theory of how the world was created goes as follows:
In the beginning there was the seed. The seed took all that was good in the universe and grew into the mighty Tree of Life. From this tree grew our world as a fruit. Everything was perfect, nothing died any everyone lived in peace and harmony. However this peace was not to last, and as death comes to all things, our world dropped from the tree of life. The world is plummeting through the void, until it shrivels and rots into a new seed for a new Tree of Life. Those that are good on this world will add their positive energy to the seed and will be reborn as gods for new worlds grown by the Tree. Those who did evil in this world will becoming the pit of the fruit of the world, doomed to be trod upon until the new Tree is grown.
Whether or not this this is true is usually debated by theologians and are mostly ignored by the common people. The farmers pray to the harvest god, the fisherman give offerings to the gods of the sea, and life goes on as it always does.