capitalism is a natural and organic stage of economic development. the class struggle you describe is central to its development, although it plays out slightly differently: "primitive" people going about surviving developed useful skills and tools, like cultivation and animal husbandry and medicine, and as these became more efficient and valuable relative to laboring, the use-value of violence rose. specifically, warrior classes appear because it is easier to make violence your labor and threaten others to hand over their labor, forcing societies to piss away resources on "guard labor" to survive. this is not "more complex," and the notion that it is is perhaps the oldest case of revisionism -- in reality, even
neanderthals enjoyed the benefits liberalism assigns to "complex" societies, which really stretches the word beyond meaning. capitalism derives power not from creating surplus, but from managing surplus, from finding the optimal amount of violence to inflict.
your analysis of wealth is true as well. indeed, hunter-gatherers can't build a hydroelectric plant. nor do they need to i suppose, but i am not a primitivist, so i can't speak to that. i like civilization. in any case, we marxists do not propose a barter economy. but we understand that capitalism will end, organically, by the same forces that birthed it. that is the whole point of lenin's warnings about imperialism, or "crony capitalism." that it is every bit as inevitable for the parasitical capitalist class to emerge and grow within the capitalist economy as it is for a warrior class to emerge within the hunter-gatherer society.
in both instances, the increasing dominance of the new class brings the system to a higher level of organization where all non-members of the dominant class (if you can't stop working while you live off passive income, that's you) are enslaved, and the lower to middle members of the dominant class become gradually relegated to working class. there is never a point where it fully implodes in a cataclysmic explosion. it's more like the centuries of slowly receding productive forces and organization you saw after the western roman empire failed to produce a new superstructure when the economic base outgrew the imperial state, where everyone was a huge doomer walking around constantly being reminded of living in the corpse of a much greater civilization.
joe biden and donald trump are both members of the parasite class, as are the UAE's elites, as are all bourgeoisie (people who can stop working and live off passive income) who participates in the global system of capital and dont turn class traitor. the parasitical class' material interests lie with bringing the system to this higher state as soon as possible. it's all organic, individual decisionmaking based on material conditions. its still happening.
in some utopian sense, communism is simply the very common-sense idea that we shouldn't have a parasite class. pretty much everyone agrees with that. the hard theoretical problem is how we get rid of them.