I'm Cannon Fodder in a Superhero World

Liang Yao inexplicably traveled to the superhero world of Manying Society, and also encountered the worst plot: the witch of despair is coming to destroy the earth! He has no superpowers and is not a superhero. After death, he can be reborn and go back to the ten days before the beginning of the main story line. What happened? How can an unarmed ordinary person survive in a world full of superheroes and facing the end of the world?