Stairway to Heaven has contrary motion in the top voice of the guitar arpeggio, which I consider a really substantial change. They did grab lots of blues songs,

Stairway to Heaven has contrary motion in the top voice of the guitar arpeggio, which I consider a really substantial change. They did grab lots of blues songs, occasionally gave some form of credit, otherwise not. It's an interesting question: blues is mostly delivery, so if you take a concept like 'lemon' or 'leave me' and deliver it in shrieky overwrought British rock star fashion, aren't you rewriting it, perhaps significantly? You can't copyright the pentatonic scale. It'd be like someone copyrighting the monotonic drone and then filing suit against half of EDM. I performed for a livestream recently and used a riff from Plastikman 'Marbles', except that riff is only note-note-rest-note-note-rest repeated infinitely on one note. Part of it is the tone and context, and I wasn't cloning that, just the way the extremely brief three-note chunk cycles over a 4/4 beat. Plagiarism? Plagiarism because I know of 'Marbles' and found it inspiring? What if I picked a simple repeating pulse because I'd heard that in some minimal techno, and intentionally did my own take on that because I'd liked it?