the most charitable interpretation of "AI can only use what it has read but can't make whole new sentences" is that even when making a supposedly new sentence, if you trace its decision tree back to the origin it plucked the word "unicorns" from some ancient forum post and got "serenaded" from a 19th century poem and just eventually pieced them together, every word was STOLEN and not original in some sense
(ignoring that everyone learned all words from SOME originating literary source in a not dissimilar manner)
(ignoring that everyone learned all words from SOME originating literary source in a not dissimilar manner)