I used to think that the printing press has been invented once and then spread, how many times has the printing press with movable types been invented?
History does not repeat but it does rhyme. Afaik as I know, two people invented the press at the same time. Before people where using woodblocks to copy works. So basically the invention was : use metal instead of wood, make enough letters so you can press anything you want.
Cast movable type was invented once and spread like wild fire.
The largest innovation from Gutenberg was finding an alloy that could withstand printing pressure and be dimensionally stable when it solidifies.