You and Jeffery are going to get along great, you both think everything Superman is doomed to fail
. I confess I don’t get how you think Superman isn’t a “big name”. Sure he can’t guarantee a big box office - but not even Batman can as seen with The Flash. Superman himself is absolutely still one of DC’s biggest brands, right now he has a movie on the way, a TV show, and an animated cartoon. He’s one of four DC characters WB chose to use in Multiversus, he’s obviously at the center of Injustice much as I dislike that franchise, and he’s one of the main Leaguers in the SS game. He’s rarely used well to my liking but he’s clearly viewed as a big deal both within WB and by the general audience.
You brought up Superman having his own live action series and cartoon, but we also have to look at the
If Legacy succeeds it makes sense to have Supergirl and the Authority in the waiting to immediately follow up on Legacy within the shared universe. If Legacy fails then the DCU will all get scrapped anyway. Only a WW movie would be a safer project to do in Phase 1. Madam Web is an example of a risky no name character getting a movie.