Re: Edge cases
You seem to have missed the crucial point that if the entire purpose of metadata is to establish "ownership", and there are multiple instances of independently produced but essentially the same works, none of which ever contained the others' metadata to begin with, then how exactly does metatdata help the Intellectual Monopolist's cause?
And that isn't an "edge case", it's the entire foundation of Intellectual Monopoly, which claims "exclusive rights" to creative works, all of which are inescapably derivative, and that's why "creative" works within each category are all so alike. Protecting metadata in verbatim copies is therefore somewhat moot, under the circumstances, if all examples of the genre are copies anyway, and even the "original" ... isn't.
Your entire argument is predicated on the assertion that these multiple instances are the rule, rather than the exception, and that all modern works are derivative. Yet the only support you've provided for this assertion is two rather weak individual cases. Prove, with valid research and statistical analysis, that the majority of modern works are significantly derivative.
You'll notice I went from "derivative" to "significantly derivative" there. This is because it's easy to argue that nearly every modern work must be derivative to some degree. But simply using the same words or key signature or imagery is not in se plagiarism. A much greater degree of similarity between an original work and a subsequent work needs to be shown to support a case of plagiarism.
Furthermore, neither of the cases you presented involved "independently produced but essentially the same" works. In the first case, the defendants were aware of the original image and of the copyright on it (one of them had previously settled for a similarly infringing work). The second case involved the sampling, or cognizant use, of a piece of music. In both cases, the latter works were produced with awareness of preceding works and thus could not be considered to be truly "independently produced."
I'm just trying to figure out why you think your so-called "edge cases" are exceptions rather than the rule
Well, partly because that's inherent in the definition of the term "edge case", but mostly because I made the apparently incorrect assumption that you wanted to provide a logical argument rather than an emotional one, and thus could be counted on to provide a significant proportion of the evidence available. If two cases are a significant proportion of the cases which fit your argument, then we are talking about exceptions rather than the rule. If, on the other hand, you have evidence that shows that a significant percentage of copyright disputes involve "independently produced but essentially the same" works, please provide it.
As for the unlimited attribution metadata you propose, that might be difficult, given the innumerable, potentially uncredited and largely forgotten or unknown contributors, spanning thousands of years...
Well, since there is no jurisdiction where copyright extends to thousands of years, that's really not a problem. While the retention of metadata past the end of copyright might be useful for academic purposes, it's not necessary from a legal standpoint.
Finally, I think I need to explain the screwdriver/nail issue a little better to you. The primary issue that metadata governance is intended to resolve is that of orphan works (and the potential abuse of that concept.) Currently, it can be difficult for an individual who wishes to use a work to identify and thus properly compensate/attribute the original creator of the work because of missing metadata (whether cause by the original creator not including metadata or by an intermediary stripping out the metadata during some conversion process.) It is also an easy exercise for a willful infringer to remove the metadata from a work and then claim ignorance. With proper metadata governance, the missing metadata would become a very rare event, and hence the claim of ignorance of the original source would be much harder to sustain. This is a completely different issue than that of recreating a photoshopped image or sampling/remixing a piece of music. It's also very different from the philosophical argument between Intellectual Monopolists, as you call them, and Creative Anarchists, as it's beginning to appear that you are.