If you were to take a novel and create visuals for everything described in the novel, with a voice-over to recite everything that's significant in the speaker-narrator's comments, the resulting film wouldn't be faithful to the original. In fact the closer the two versions, the more likely the filmed version won't seem "faithful." Conversely, a careful novelization of a particular movie will not read as "faithful" to the original.

Movies don't unroll in the audience's mind the way that novels do.

Even if there were no differences of genre, you couldn't produce a faithful second version--remakes of films that use the same storyline shot-by-shot are nothing like the original.

Ditto for novels, even if they are photocopied: https://en.wikipedia.org/wiki/Pierre_Menard,_Author_of_the_Quixote