1) There is magic, but it is uncommon, and only a few special people (who usually have some kind of birth mark) can use it. Others may use it by making a pact with a supernatural entity.
2) There is only one (known) continent and only a few small islands. Large ships are almost completely unknown; sailors are typically sailing either cargo ships typically around 40-50 feet long, or smaller fishing boats.
3) Humans are the only mortal race living on the continent, and are the third mortal race to be created. The other two races were destroyed by cataclysmic events before being replaced.
4) A cycle of destruction ravages the continent every 1000 years, dust storms and insane heat waves drying it to a bone.
5) Massive gemstones dot the land. They are the source of magic, and can be used as a focus to commune with various supernatural entities.
6) Magic radiating from the gems and the influence of the various supernatural entities greatly speed up evolution, with life going from slimes to intelligent, mortal race in the first 300 years of each cycle. It is not uncommon for a child to look like he belong to another subspecies from his parents.
Sooo... I think the third rule can be amended by stating that the "human only" part only apply to the third cycle. Which may or may not be the main focus of the story, depends.
Other than that it's coherent and very interesting.
Just one thing: the wording of rule three and four might point out that the island around the continent are unharmed by the cataclysms. Leftovers of earlier civilisations might remain here...