Rebirth in Time and Space, the General's Daughter

Fang Heshi, a college student, inexplicably entered a book that he read in full in junior high school. As soon as he entered, he went to the battlefield and was killed by the male protagonist alone? After being single-handedly killed, he had to be reborn to help the author rewrite the ending of the heroine Fang Li in the original book? What's the point of this? It's too weird...