any ideas I can add to one of my first stories ever? The world became overrun by demons, humans are no longer the apex predator. This was a plan that conspired in hell as the ultimate attack against God. In response, God sent angels to bless Humans with power and send them back to where they came from. The Demon's objective is to consume the hearts of all living creatures on earth by consuming their hearts, our protagonist was, unfortunately, victim to one of the biggest catastrophes by the demons. miraculously before turning into a Demon, an old man saved his life for unknown reasons and nurtures this young goy at the time to gain vengeance against the demons. He later discovers however, he's been long dead, yet alive. He's a half-demon. Now struggling with his identity he seeks to end demons once and for all whilst blocking his carnal natural desires of killing humans. And to answer the question, is he a part of those monsters? How would the friends he's made along the way think? What does it mean to be alive?
Sounds interesting but I think it's been done before, but regardless I hope you'll make it unique when you actually write the story.
Sounds more or less like Demon Slayer (Kimetsu no Yaiba), one of the most wildly successful anime of the last few years.
I'm sorry if I'm not helpful, but I can't help but be what I am. Start with what you want to say. Your theme. Your message. All the plots and worlds and characters come to serve that. What do you think? What do you think it means to be alive? What is identity? I imagine you think there is something more to it than genetics. Then you should craft a plot where the characters are challenged to ask themselves this question and they come out with the answer that there is more to it than genetics. Of course, then you might ask yourself why you think this story needs to be told, if it's already been told before. Perhaps you're telling it in a new way. Perhaps you're just telling it for yourself or for the lovely people who will read your new book instead of the ancient scrolls that tell the same story in indecipherable Old English. What makes a man? His thoughts or his actions? What would you think about a serial killer who never killed anyone but committed his life to philanthropy? What would you think of a child who killed but then grew up to be a sweet philanthropist? How about a philanthropist who suddenly snapped and killed one person? Does only the latest action matter?