Correct me if I'm wrong, but we don't actually know what system of government Marley uses. I'm curious as to whether they are a monarchy (and if so, constitutional or absolute), a republic or something along the lines of a fascist or military dictatorship. Their treatment of the Eldians does draw a close parralel with Nazi Germany and the holocaust, and indeed both Eldia and Marley appear to be at least somewhat Germanic (all white, lots of blonde hair, large number of German names). Personally I think they're most likely to be a constitutional monarchy along the lines of the German or Japanese Empires, as they appear somewhat militarist but not to an extreme level like you'd expect from fascists.
We don't know at this point. It's funny that people always bring up Nazy Germany, and the parallels are there, but there's an element that also reminds me of the treatment of Japanese Americans in WW2 and no one ever mentions it. The Eldians who are part of the warriors program remind me of the Japanese who fought for the US during WW2 because they badly wanted to prove their loyalty to their adopted country, even while their families were stuck in internment camps.
It's probably a less popular connection since the Marleyans are considered the bad guys, but given the focus in the latest chapters and that Magath doesn't seem to be a giant bigot, I tend to view them as just another culture we just don't know that well yet.
I'd like them to be something other than a monarchy though, just because it would be a starker contrast to the Eldians, who do have a monarchy. It could be another reason for a divide in their worldviews.
That's an interesting parallel for Japan and the USA, quite possible too. I agree that a difference in ideologies would make for a good narrative aspect. But even just the Eldians having a constitution and Marley being absolutists would be a big difference.
I think we're inclined to assume Marley is autocratic because that's "bad", but I for one would like them to be Republicans. The idea that the "will of the people" could be skewed towards such an aggressive view point could be interesting, as we tend to have a (rather unfounded) idea that democracies are "good". Of course the series has thus far shown that a nation and its people are neither good nor bad, an aspect I very much like.
(1) I mean, I think we can see so many conflicts and wars in SNK. The Israeli-Palestinian conflict or the Genocide in Rwanda come to mind for instance (plus every conflicts you mentionned).
(2) I believe that Hajime Isayama emphazised more on the collective memory of civilizations, a strong sociological aspects that can be manipulated for political ends. So I think no matter the marley's regime, the critic of political elites and their manipulations of societal dymamics is still there. The complex duality between oppressed and oppressor (good vs bad) is also presented because this is partly driven by the collective memory of people (and it's alteration).
Wars and social conflicts is a bunch of misunderstandings of other's culture, history, background, etc but also of political and economic interests and manipulation of collective thinking. And very often, there are groups that get the repercussions more badly than others.
I agree that if Marley is a democratic regime, it will strongly support the latter statement, but I think it's not the fundamental debate here. The debate seems to be on the manipulation of collective memory from elites (often for personnal interests) no matter the regime, and the oppressed/oppressor dichotomy resulting from this which brings us finally to the question of good and bad. So yeah, I look foward to discover the type of regime, but even if Isayama doesn't specified the type, the social issue remain the same and thus the following philosophical questions: is there an objective definition of good and bad? If so, what is good and what is bad?
Anyway, I thought SNK was cool and the kind of show that gives me goosebump because the characters are cool and badass, but now it gives me goosebumps because this is a well-build sociological presentation of war and social conflicts.