Trying to Survive in a World That Has Lost Its Protagonist

[Through the book to know the plot + Retrospective ability + Multi-race + Single female protagonist] This is a world in a book, a world with elemental magic. Mobien accidentally traveled here, and accidentally discovered that the original protagonist, Caesar, who was supposed to save the world in the book, disappeared. Without the powerful plug-ins of the original protagonist, the world has fallen into a precarious situation. In order to get the life and survive in this world. Mobien, who traveled here, resolutely took on the name of "Savior", but he did not have as powerful a plug-in as the original protagonist. After inheriting the original heroine and planning various events, he had the ability to look back in a short time... The protagonists who were originally just enriching the plot seemed to have become the real savior. Under his guidance, they seemed to look at themselves differently, especially Olivia. What was wrong with this guy? Why did he always look jealous? She was the one who said she didn't want to be his mistress at the beginning... (Ps: The backtracking ability will be reflected in Chapter 20)