I tend to avoid things like creation myths and religion on general principle. If I had created a awesome map that no one could beat I wouldn't be happy to find out that someone had stolen it and marketed it for millions, so why should I try to create a god?

To be honest I don't think the average western Joe would care that much about yet another creation myth. However I do give my readers a starting point of some sort.

An example: Wizard A grows up in village being mentored by Wizard B. A discovers immortality. 9 million years later the story starts as Wizard A picks up an apprentice called Wizard C. Wizard C is the Hero/Heroine and over time learns about Wizard A and the World. Plot devices to bind Wizard A's power may be necessary.

The origin myth substitute is that before Wizard A people just lived in villages doing not much. It even comes with shake 'n' bake villains as Wizard C discovers Wizard A's enemies.