Screw lore.
You are in a world which is totally not a result of incorrect worldmapping, and you only goal is to get diamonds (and possibly gold). However, you will find the terrain harsh and difficult to navigate. Luckily, you have acess to a small amount of supplies, and they should keep you alive long enough to complete your quest.

Also, the first one to post a picture or video of themself mining a diamond gets an honorary mention in one of my later maps!