Do you really think all those authors/mangaka experienced the events they let their characters go through? No. They use their imagination. Do you think Kishimoto-sensei experienced even half of the traumatic events that occur in Naruto? No. Yet he must have done a pretty damn good job bringing over those emotions, right? Otherwise you wouldn't constantly make threads surrounding this particular subject.Imagination is usable for kindergarteners during play time. You can maybe experience with your imagination, what it feels like for a moment, not every minute of everyday of your life.
If you pass off this story as just another form of entertainment, then I have never seen such waste.
His manga isn't meant to experience those emotions every day for the rest of your life. He wants to drag you in the story, let you experience the story and then when you're done reading, go back to the real world while occassionally thinking about some of the messages.
And yes this story is one of the many forms of entertainment that exist. It's a shonen manga, and it's classified as action. Not as a slice of life story. This story is meant as an entertainment form, not as a piece to be all philosophical about.
And imagination, that thing you consider only useful for kindergarten teachers apparently, has made various authors/mangaka very rich, so it can't be only suitable for kindergarten teachers then, right?
If you want to be philosophical about this story - even though there isn't a need to - fine, that's your right. But considering it's an action themed manga, aimed at teenage boys, excuse me if I don't act all philosophical about it.
You can discuss a character's personality pretty well if you take the time to study it (like some of us do) and that doesn't mean you have to go through the same experiences as that character. That's why imagination is so useful