Can you name a historical society where there wasn't any manner of "aristocratic ruling class"?
It is a historical constant that rich people are more likely to find themselves in office. Campaigning takes time and effort and you don't get paid for it, so you pretty much have to have some wealth stashed up before you can run for office. That was true then as it is true now.
That doesn't mean that there has never been a democratic government in all of history. No matter how wealthy you are, in order to get those jobs, you have to convince people to vote for you.
I didn't say that there has never been a democratic government in all of history. I said that the Roman Republic could not in any sense of the word be described as democratic. It was fundamentally and wholly governed by wealthy land-owning elites, who derived their position in the system from their wealth, despite the presence of institutions that bear a superficial similarity to institutions present in modern democracies.
I'd really urge you to crack open an academic textbook on the subject. If you'd like to dive a little deeper, I'd recommend W.G. Runciman, "Capitalism Without Classes: The Case of Ancient Rome" (British Journal of Sociology), Wilfried Nippel, "Policing Rome" (Journal of Roman Studies), Peter Baehr, "Caesar and the Fading of the Roman World", Peter Brunt, "The Army and the Land in the Roman Revolution" and Douglass North, "Institutions, Institutional Change, and Economic Performance" which has a large stretch of summary of Roman political economy.
It is a historical constant that rich people are more likely to find themselves in office. Campaigning takes time and effort and you don't get paid for it, so you pretty much have to have some wealth stashed up before you can run for office. That was true then as it is true now.
That doesn't mean that there has never been a democratic government in all of history. No matter how wealthy you are, in order to get those jobs, you have to convince people to vote for you.