Unseen influences from within metal:
4. Atheist, raised the ante for prog metal to exist
6. Human Remains, created second generation hardcore, all nu-metal/metalcore is based on this
There's nothing "unseen" or controversial about the rest of the metal list, but these are (atleast as how you present them) bordering on ahistorical. Atheist is one of those bands everyone seems to love but, outside of busier rhythm sections and a thin veneer of jazziness, really hasn't had a lot of direct influence. In fact, Cynic are the likelier source of innovating/popularizing this particular tendency and Watchtower, Dream Theater and every other technical thrash band either predate or are contemporary with Atheist.
I'm also not really seeing the historical justification for listing any one band (let alone Human Remains) as the
sole progenitor of nu-metal. For nu-metal it's more helpful to look at broader trends in mainstream hard rock/metal - funk metal, groove metal/post-thrash, earlier hip-hop w/metal samples and the overall grunge aesthetic are all more relevant developments imo. As far as hardcore goes, I think groups like Rorschach or Heroin among many others in the late 80's/early 90s shaped modern hardcore in a far more observable manner.
What I'd really like to know is which asshole was the first to shit out the obnoxious "secundal screech far up the neck + open power chord" riff.