i'm not familiar w good critical refutation.

I don't think capitalism can keep collapsing and reforming forever. Extinction is possible (nuclear war, maybe climate change), and different economic systems are possible. The key thing is that as long as there are contradictions, there will be change. Under capitalism the biggest one is within the mode of production: capitalists organize labor in a way which results in great inefficiency and suffering, and this produces a class of workers who are incentivized to change the system. The longer capitalism goes on, the larger and more definite the working class becomes, sharpening this contradiction. Eventually something has to release the pressure: socialist revolution (likely via a DoP, which will have its own contradictions to work through on the way to communism), or a reconfiguration of classes into some new arrangement which will result in a different kind of conflict than bourgeois-proletariat. Social upheaval can blow off steam without fundamentally changing class relations, but pressure will just keep building up and it's unreasonable to expect infinite, e.g., BLM outbursts to never turn into something more. Nukes may kill us all at once, but I think it's likely that even though climate crisis will cause vast devastation, this will increase class conflict and therefore opportunities to resolve these new contradictions.

the way I see it, all societies fall into

• some class is in control (nobility = feudalism, bourgeoisie = capitalism, workers = dictatorship of proletariat, etc). resolving contradictions can lead to communism
• there aren't coherent classes. communism (primitive or otherwise)

the theory of marxism can be applied perfectly fine to indigenous societies. go down and see if there are classes and what they're doing in the same way as e.g. Mao in Hunan. you may very well find that there is not a proletariat! marxism doesn't say that there will always be a working class, just that capitalism builds one

Lenin said that communism won't simply emerge spontaneously and that it needs to be agitated for by people and communist parties. If we believe that capitalism is a European ideology that emerged from the material conditions of Europe, then it's antithesis communism should be the same, right?

Well communism isn't gonna emerge with a snap of the fingers, but what is guaranteed as long as we have classes is that there are going to be people who figure out what's going on. Those are the ones Lenin said must struggle in order to get to communism. Marxism was discovered in European context, but it applies just as well whenever you've got classes and I don't see any reason why it won't keep getting rediscovered in different contexts if the original strain goes extinct.