Even though there may not be anything new—new ideas do pop up from time to time actually—there are universal ideas and beliefs among other things that are still in existence, and there are boundless new ways you can express them, especially in fiction writing.
You can re-hash old ideas once you are clear about your topic of choice. Thereafter, it’s all about style and the spin you put on it that will make your writing unique.
So don’t be dissuaded, there are endless possibilities to be creative with old and over-used ideas.
Get the idea, established your story plot, be passionate about it and get to writing.
Tip: Look around your local community and beyond. Contact any PR department i.e hospital, police, school, social services, football/soccer clubs etc. etc. You’ll be inspired.