Apparently the people are complaining because they are suffering for the wrongdoing of their parents. They weren’t the ones who sinned and caused the defeat of Judah, but they are the ones who have to live in captivity. God assures them he treats each person individually. God deals with everyone fairly.
There is truth in the people’s complaint. Their current circumstances have been affected by the decisions of their parents. That’s true for all of us. If you had bad parents, you suffered. If you had good ones, you benefited. But God lets them know they will each be judged by their own decisions. We each need to trust Christ for ourselves. If our parents trusted Christ, that’s great, but it doesn’t do us any good unless we follow their example. If our parents didn’t trust Christ, that’s no excuse for us not to do so for ourselves.