Woah I'm so impressed by the quality of this post. I enjoyed reading it so much while listening to the music, I'm now re-reading it and re-listening to process all of it. I knew Portishead's song but I did not identified a sample on the theme's progression.

I think this is an interested topic and sometimes we really do take for granted how much of music is produced inspired in previous works. For example, I clearly hear the Swan Lake's motive in "Daydream"... Also, I remember the first time I heard Rachmaninoff's Piano Concerto nº2 and recognised the theme of another song: Eric Carmen's "All by myself". Now, I consider plagiarism to be a delicate topic, especially since the 90's, so I won't get into that on this comment. But I do think that there are some "unintentional plagiarisms" in music that are truly inevitable. I think music, like matter, is not created or destroyed, but transformed.

Some musicians may take it as a compliment that other artists feel inspired in their work, others don't (of course, it depends on the degree of their "inspiration")... what do you think Hayes would think about all the uses of his samples that he didn't get to hear?

Great post!