Our gods did not anticipate for how far we would progress. They expected humanity to endure for a generation, perhaps a few if we were fortunate. They created an afterlife for those who passed away—a loving mansion, brimming with everything one could desire. It seems infinite, but the key word here is "seems."
Stretching approximately thirty kilometers in width and fourteen in length, the house is undeniably massive, of course. But to label it as infinite would be an exaggeration.
Yet, with every person who died, they were sent to that mansion. The initial generations were content, and the following ones as well.
A couple hundred years later, however, it began to feel a little crowded. Not as much room for oneself. Of course it was livable; they didn't have a choice in the matter.
It filled up, leaving less room to move or even think to oneself. Despite being in the afterlife, where one simply cannot die, more souls filled its walls. Eventually, it became impossible to move.
The gods didn't watch us; they abandoned us to grow and expand our horizons. And we did.
Famine. War. Conquest. All of these brought more and more death. The world grew. Populations boomed. The living prospered, while the dead suffered.
Through broken bones, liquefied flesh, and frayed nerves, more and more came.
And so it has been, and so it shall be, for all the rest of time.