Edit: Take this with a grain of salt. A big grain of salt if required.
Okay, I'm happy to say I'm wrong... I don't want to offend anyone so I'll happily say I'm wrong. I'm not sure if I'm actually wrong, but I'm not sure that I'm right either, so there's that
I will admit, when it comes to the legal side of all of this, I do have no clue (well probably not "no clue") but very little of a clue. So from now I'm down with whatever Ampersand / you / whoever said or says.
From what I'm reading here: The legal side seems to be if you based work off someone else's in an intentional manner then that is good enough to be classed as plagiarism. If the artist changes enough things maybe it wouldn't go noticed... but, that's not the point, it would still be plagiarism. If the legal intepretation is that... or close to that... I'm down with that. I won't argue with it if it's right.
So perhaps I'm arguing about the wrong thing here (very likely), but "legal" stuff aside, I still think there's undeniable ambiguity between what makes something original and what makes something a copy. I think everyone knows these lines are not clear. Again, I'll accept you guys are right on legal side.
A thought experiment:
Like say I come across the most awesome green pixel I've ever seen (created by another artist). And I decide I'm going to copy... yep that's right I'm going to steal this green pixel. To make things a bit more interesting I've decided I'm not going to use the colour dropper... in fact I'm going to spice things up and work out the colour by sight!! So I do that. Now I've got my plagiarised green pixel. Nice!
So then on the other side of the world, somebody else decides by some divine inspiration to draw a green pixel. By sheer chance it's a similar green to what I chose (and therefore the original artist). This however is agreeably not plagiarised (despite looking the same, there's only so much you can do with 1x1 pixel AND the person didnt copy the original so it's fine). It's a very boring piece of work, but it's not plagiarised.
Then actually, it turns out the artist on the other side of the world had seen the green pixel somewhere else and it wasn't divide inspiration at all! This thought experiment was weird to begin, but now it became super weird
[edit: even if you don't agree with the point of the "thought experiment"... surely you can see at least some merit it]
I hear this exact kind of thing in music all the time. In the past I was so paranoid about this I intentionally changed melodies in my own music (with the fear they weren't original). Fortunately I don't think like this as much now.
Like if you play me a piece of music, often I can hear the influences very clearly. I'm sure you / others get this too. And recently I was studying lots of music from 70's, 80's (Kansas in particular), and I could see how they influenced bands like Dream Theater, Amorphis, Metallica etc. Sometimes the link is hazy but other times you can almost say with high certaintity that one idea is based off another. Often the end result might be different but you get this
intuitive feeling that enough moving parts line up for it to be intentional. And I think that should be fine!
[edit: perhaps in the case of Pigeon Pop you have far too many elements lining up]
Maybe it's silly to try and make an analogue with music as it has a
relatively "lower resolution" (actually, this could be debated) in terms of what you can express when compared to visual art.