Discover - to find films by genre for example https://developers.themoviedb.org/3/discover/movie-discover
Genre list https://developers.themoviedb.org/3/genres/get-movie-list
Lists - can get for a specific movie https://developers.themoviedb.org/3/movies/get-movie-lists
Movies - popular and top-rated might be a good source https://developers.themoviedb.org/3/movies/get-popular-movies
Trending Movies https://developers.themoviedb.org/3/trending/get-trending
Search - keywords, movies and people might be useful https://developers.themoviedb.org/3/search/search-keywords