Cosmology : first draft
All souls find their origin in a Greater Being. In a cosmological event, that Being got "fractured" and lost parts , tiny dust-size , sparkles of itself, that becames souls. All those fragments try to rejoin with the original part.
But they cannot.
Because the gods wish to gather as much souls as they can in order to harness the power inherent to souls.
Most racial gods (affiliated to a particular race) made a pact : they would gather the souls from a race. But some other gods, more chaotic and greedy, chose to size with no one, and hunt souls whereever they can.
so we have no good gods, only power-hungry.
Some of them behave in a lawfull way and seemingly with benevolence toward a specific race.
There's room to invent a creation mythos, several gods, and lesser gods working for them in hope to gain a part of the power greater gods could have.
The Afterlife is a maze designed to lose the souls and hide the way back to the Progenitor. But the Greater Being, though Reality is veiled from Him by the gods, is not powerless. He created the reincarnation cycle as a safety exit from the Maze, in order to give souls another chance to rejoin with him, should they fail upon the attempt they're given at death.