It's so Hard to Be a Savior

David's soul traveled to another world, and what he saw when he opened his eyes was a modern civilized society similar to the Victorian era. Steam trains, giant ships and cannons, prosperous cities, and factory chimneys. Everything seems to be no different from that time on earth. David has grown up here slowly since he was a baby, studying, graduating, working and living here. He originally thought that this was an ordinary world, and his life would probably be as ordinary as it was on the earth plane. But a chance acquaintance led him into the hidden and extraordinary realm of this world. Meditation, potions, spell casting, spiritual rejuvenation. David's eyes were opened and he quickly became a wizard with extraordinary abilities. But the good times didn't last long, just when David was working hard to practice and improve himself quickly. The world he was in was invaded by people from another world. The invaders were extremely powerful, and in a short period of time, David's world was basically destroyed and fell. The human resistance coalition was retreating steadily, and in the final battle, it was finally defeated. David, as a member of the resistance coalition, also died in this final battle. But when he opened his eyes again, he found that he was reborn and returned to the time when he had just graduated from college more than 20 years ago. At this time, it seems that he is the only one in the world who knows that the end is coming. But he has all the memories of various events that happened in this world in the next twenty years. There are countless undiscovered treasures and various opportunities to strengthen your own strength. So, a certain being resurrected him to be the savior of this world?