Everyone has awakened, but I am the only mortal!

In the first year of the apocalypse, human civilization teetered on the brink of destruction. The sole ironclad rule for all humanity (which everyone firmly believed) was: enter the gap → survive → inevitably absorb the spirit → inevitably gain power. No one was an exception. Except for the protagonist. In this post-apocalyptic world teeming with monsters, where rules devour humanity, and no one is perfect, how could a thoroughly "mortal" survive?