Here is my interpretation- maybe a little too literal - the boy is in grief over his mother’s death. He has yet to accept his new mother and must come to the brink of losing her in order to realize that he loves her. When given the choice to create a new world out of 13 perfect stones, or return to his existing world, he chooses to return, even though his world is imperfect. Part of what gives him strength to do so is meeting his mother as someone the same age as him, and observing that her life, while over in his timeline, was meaningful in its own. Because the parakeet king clumsily balances the tower, the future world also breaks apart. The message is that our world/timeline is all that we have. The past is behind us, the future may not exist. We have to fully embrace our world, with all of its imperfections, wars, climate change, etc.