Humanity Collectively Traveled Through Time, but I Was Abandoned

Have I been forgotten by the whole world? When everyone traveled to another world, I was protecting the earth alone. My legend begins when humans return and then the cataclysm occurs. —————————————————————— The earth is about to evolve to another stage. In order to prevent human beings from becoming extinct, God sends all human beings to a different world that already has magic power to practice, but the protagonist is left alone on earth. In order to survive in the future, the protagonist can only work hard to train on this desolate earth... This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.