The exploration of death is inevitable in a superhero story.
Not to be confused with the loss that often makes the hero, this exploration of death is of the loss which occurs during and perhaps because of being a superhero. Batman has already lost a Robin. In Marvel, Spider-man has lost a girlfriend.
A hero is supposed to save lives so what questions and doubts does death raise?
With great power there must also come, great responsibility.
Peter Parker’s biggest regret and therefore the greatest lesson about having powers is what made the above arguably the most famous quote of Spider-man.