Well there's a lot more here, look under Siegel and Schuster here:
https://www.supermanthroughtheages.com/a/creators.phpEssentially, however, the story "The Superman" with the character being a villain was pitched as a pulp book (published in an inexpensive format). Superman as a comic was drawn for newspaper publication, not picked up, then cut and pasted by hand for Action Comics in 1938.