Survival in a Cold World: the End of the World with No Return

After half an hour of reading, I found that the work became more and more surprising as I read further. The description of the details is very good, but there are also areas for improvement. If there is something wrong, please give me some advice: First, the author laid the groundwork in the first three chapters to introduce the protagonist, but in my opinion, this is not necessary. The content of the first three chapters can be explained directly in a few words in the fourth chapter. Second, the background of the protagonist can be explained more. After all, in this apocalyptic world, it is difficult to survive without basic survival skills and means. And this is not enough for scientists alone. Third, animals can mutate. As humans, is it possible to mutate? Otherwise, when faced with mutated animals such as bears, simply discovering weaknesses is not enough. Fourth, the detailed description is in place in some places, but in other places the storyline progresses too fast. There should also be an explanation of the previous development level of the city where the protagonist is located, its environment and geographical location.