Cosmic forces and Sanzeia

By analogy, if you were to think of Sanzeia as a one single living being then the Gods occupy the role of the being's mind. They have power and control over the whole and are working towards a known (at least to them) goal of their own. The various Gods would then represent facets of the being's personality, and while their focus, methods, and interpretation of the goal might vary, all basically are working towards that common goal in some way. The various races placed by the Gods on Sanzeia thus have some role to play in the cosmic plan of the divine.
The elemental power that formed Sanzeia would then represent the body itself. The dragons, as the foremost embodiment of the planet's elemental will would then have the roll of the the body's immune system. These forces initially and at times work against the mind's conscious desire, but in general are at least in different to the plans of the Gods. If the elements of Sanzeia can be said to have a goal, it would be the continuance of the planet itself; the existence of a single race, mountain, or continent is ultimately irrelevant if the planet survives.
Then there are the forces from outside of Sanzeia. The fey creatures from the parallel planes of life and shadow could be seen as balanced force, with one side seeking to spread life across the surface of Sanzeia and one to make sure that that life ends and does not overwhelm the material world.
The demons of chaos and the Abyss then form the primary threat to the body of Sanzeia in that they seek to destroy and corrupt all existence, something that no other cosmic force could desire. 
The devils of the hells occupy a similar role to the divine, in that they seek to enact and force the obedience to some sort of plan and above all else seek to contain and thwart the destructive aims of the forces of Chaos. Their implementation would likely differ highly from the (generally) more benevolent gods.