You said that it is always just for God to do as he wishes with his creation. This implies to me that anything God does with his creation is just - which robs the concept of its meaning. Did I misunderstand you? Could you explain what you meant by that?

Regarding children - have you never seen young children being spontaneously nice to each other then? Have you never seen them display sympathy towards others? If we have no altruistic inclinations at all from a young age, then I'm baffled as to how we developed the moral system we have now in the first place.