To clarify, is your position that democracy means regular change in position of the head of state? In that case, President Miguel Diáz-Canel isn't related to the Castros at all, so your cause for concern should be alleviated. Personally, I don't see authority and democracy as contradictory, all States are monopolies on violence, as I said. Democracy in my view is rule by the majority, which I see as rule by the working classes. Cuba has a complex system of democracy that goes above western conceptions of democracy.

Cuba has what they call a participatory democracy. People participate in all levels of government, and the government is led by the PCC. The democratic structure relies on delegates sent to the various organs of government from among the people, and this translates into popular rule by the working classes themselves.

Long-serving leaders are not indicative of a lack of democracy, but more towards stability. In the context of a country under siege, stability is critical, and regular turnover introduces chaos that they cannot afford. In fact, the low term limits of leaders in countries like the US are there to prevent lasting change from ever happening, and instead let the ongoing background processes take priority, those processes being capitalism and imperialism.

Ah okay more of a piggyback critique on others' use of it than of mine, gotcha.

Off the bat, this is bafflingly wrong in a few areas, but you seem to be aware of the problem already. Parenti is less a Marxist and more of a "pro-Marxist," he supports Marxism and revolution without being an actual scholar of Marxism. Žižek is a Hegelian, not a Marxist, and moreover is an opportunist clown that capes for western imperialism through a "left" angle. As such, you have a few critical flaws in your points.

The revolution will definitely happen spontaneously.

This isn't the Marxist point. Marxism is not determinist in this manner, the point is that as the contradiction between socialization of labor and privatization of profits grows, revolutionary pressure will increase. Spontaneity can only get you so far, though, ultimately you have to organize for revolution, and create the vehicles for aligning the working classes. All successful revolutions have relied upon such mechanisms.

People actually want a fair system and definitely don’t just wish to feel superior.

This is again, not a Marxist point. People's way of thinking comes from their material conditions, not any intrinsic human nature. This is well documented by Anna Louise Strong, a Statesian journalist that spent a great deal of time reporting on revolutionary governments in the 20th century:

The difference appears in the use of pronouns. People under capitalism are contrasting “I” and “they.” “Too bad it couldn’t have been on my land,” a man remarks of a California oil-strike. Soviet folk would be hailing “our new oil-wells”; to them the idea of a private oil-well is already as quaint as a private postal system. I note a remark about American unemployment: “If it gets any worse, they’ll have to do something.” Who is this ultimate, uncontrollable “they”? The term betrays the class society of which the speakers are unconscious; they are waiting for some boss to act. To hear a debate: “Is America going fascist?” and think how much less passively Soviet folk would word it. “Shall we go fascist? No. Then exactly how shall we prevent it?” Soviet folk say “we” of one-sixth of the earth’s surface. Uzbek cotton-pickers, toiling under the sun of Central Asia, say: “We are conquering the Arctic; we rescued the Chelyuskinites.” Ukrainian farmers who never went up in an airplane talk of “our stratosphere records” and “the loss of our Maxim Gorky airplane” as they take up collections to build ten new ones. But even Mrs. Roosevelt asks me: “Are Russian peasants getting more reconciled to accepting direction?” I feel the hopelessness of language as I answer: “No, they are learning better to organize and direct themselves.”

I know it's a bit of a meme for people to say "ours" and "we," adding "comrade," but it genuinely is the lived experience of people living in socialist society. This was written in 1936, in a book titled This Soviet World. The important note here is that the way we think depends on the way we live, the way we produce and distribute. People want to get more than their neighbors not because of any intrinsic desire, but because capitalism molds humans to do so. Just as capitalism molds humans, so too does socialism, in a more communal direction.

The role of the vanguard is to educate the rest of the working classes, bringing them up to their level of political engagement and knowledge. This is why Anna Louise Strong said the Russian peasantry were learning better to organize and direct themselves, not merely to be led passively. This ongoing pedagogical obstacle is the chief concern of communist parties, and it actually does work.

As for the dictatorship of the proletariat, it's the dictatorial rule of a class over the rest. It isn't a dictatorship outright, in that it's democratic for the class in power. In capitalism, democracy extends to capitalists alone. In socialism, it's the proletariat that enjoys democracy, and its the landlords, fascists, and capitalists denied that right.

All in all, I know saying "read Marx" is a meme, a horribly ineffective one at that, but I do think that if you have problems with an ideology, you should actually visit the source.