Global Catastrophe: I Became Mankind's Only Cheat

Global catastrophe, when you are still feeling hopeless. A man has appeared behind you and extended his right hand to you. "Who is that? My time is limited, so I will lend you my body. How about giving me some superpower as reward afterwards?" As a result, the whole world changed dramatically after that day. Catastrophe! Damn it, why don't we have a disaster here? How can we obtain superpowers without catastrophe?