I've read the status of the Superman scripts given to Richard Donner (although not the original Mario Puzo ones, which I'd kill to read). They were...goofy.

The main plot beats are there for both Superman 1 and 2, but the attitude is very different. It's clear the Salkinds wanted a campy 1960s Batman feel to the movies and Richard Donner and Tom Manckewicz brought some real down-to-earthness to the script. Pun intended.

Superman 3 was the kind of movie the Salkinds wanted for 1 and 2. And that...wasn't good.

https://fandomwire.com/it-was-disparaging-richard-donner-revealed-original-superman-script-with-marlon-brando-wouldve-killed-the-superhero-genre-forever/