The best answer to this question is that you have to search for “livres faciles” or “romans faciles” even in the google. The keyword for your search is the word “facile”. I searched it and I found many titles (or even many texts). You do it yourself.
In high school French class, we read Volkswagen Blues and Le Petit Prince. Im not sure what you mean by 1500 French level, but they would be good books to check out.