"So even if you guys wanted to be strong and be like them, there's no need to rush to experience killing people at all.
You don't necessarily get stronger if you kill people, so just continue working hard and training yourselves and killing zombies."
They were already doing a good job of killing zombies, so there's really no need for them to kill other people if it isn't necessary.
They already had a hard time when they first killed zombies, so it's obvious that they would have a harder time killing people.
"But isn't it better to experience now than later and freeze because we are scared? At least we still have cousin Treyton and the others to protect us," Astrid said.
Luciel knew that Astrid was worried that if they encountered danger someday because of people and had to kill others before they would get killed, they might not be able to do it because they got scared.