How often has DC been successful with new original/non-legacy characters? Harley Quinn 30 years ago and the New Teen Titans characters 40 years ago? Harley shouldn’t even count because she debuted on one of the most popular cartoons of all time and then appeared in comics.
They’re only relatively successful new characters since Harley are Damien Wayne and Jaime. Two legacy characters.
The legacy aspect usually creates fan wars and I’m not generally a fan of it but I think Jaime would have quickly faded into obscurity if he wasn’t a legacy.