(These are only airy theories, don't take any of them seriously.)
People who are older- 30+, seems to be discarded when it comes to the tragedy factor of death.
Kids, are considered a high tragedy.
There is a natural order of likeliness of death. This is revealed, as of now.
When one is thirteen, her or she is blissfully the least vulnerable to death (excluding blatant stupidity.) He or she feels very fresh and alive. They have no fear of death, because their world is crystal clear. This enables their path to be clean, unhazardous, and ready for danger. They don't consider death, and death doesn't consider them.