The denizens of a planet are what make it what it is. They mine its caves; they harvest its plants; they hunt its animals. They are the people that truly define the way of life.
They are the heroes of their own stories-- or, perhaps, the villains of others'. They may take many forms, or walk many paths. They are the ones who define the features of the planet, who shape it and make it what it is. Inventors and creators, changers and destroyers.
The world exists for those heroes, the people who live in it, and they are what makes the sun rise and fall on that world. They are the blood that pumps in Moebius's veins, the fuel that sustains it.