Think about it.
You write a movie based on the silent version of The Ten Commandments.
You compose a song based around the tune of Happy Birthday.
Those are just some of the examples that one can do without fear of infringing on anyone's copyright because on January 1, 2019 many classics in the world of books, movies and music became part of the public domain. Basically, those classics' copyrights had expired and now could be YOURS FOR FREE; pretty much anything created before 1923 is in the public domain.
If I recall, there are original Disney classics that have been reinterpreted over the years because their copyrights had expired and became fair game for anyone. In return, much of those classics were given a fresh take, much to the delight or chagrin of the consumer. Basically, people either loved new retellings of those stories or hated it because they altered the premise of said storylines.
So get your pen to paper and get creative! Or at least get inspired by those old classics now in the public domain and retell them in a way that becomes your vision of the story...
TheGuardian.com has a great article detailing on how much of those classics are now for public consumption without fear of copyright infringement. Check out the link below.