I would argue that the original author retained the copyright and mine is a derivative work.
If I took a film, and re-enacted the scenes, does my film infringe upon the original film?
This is a bit ambiguous, if the film were presented as parody for example, but you'd still out of courtesy, contact the copyright owners and see if they / their lawyers think it's infringing before spending years doing so
If I took someone's game, recreated it from scratch, and made a youtube video tutorial, "how to make this game including indistinguishable graphics, textures and gameplay" would the resulting video be infringing?
Even more ambiguous than the last example - if the language stated "similar to" and the resultant product was distinguishable in some way, I think it wouldn't infringe.
My gut feel is that guitar tabs is simplified sheet music - and sheet music is copyrightable, because even if the the play style of the artist is slightly different from the original, the arrangement of the music is what is copyrightable, and the original authors deserve at least some of the proceeds from the use of that copyright