If you were really well informed about the Roman republic, you'd know that it was an oligarchic republic, with one of the most fiddled "democracies" in history. They voted by tribes. Originally, there were three tribes. So, 51% of two tribes could vote for a measure, and 100% of the third tribe could vote against it, and it would pass--despite the fact that only marginally more than one third of the people had voted for the measure. All legislation was proposed by the Senate, an exclusive club the members of which were appointed by the Censor.
In Athens, less than 10% of the male population had the vote--no women had the vote. Slaves and "foreigners' (anyone not born in Attica) could not vote, and no citizen of Attica who was not also a freeholder in the city of Athens could vote. At the time of the ratification of the American constitution, there was universal, white manhood sufferage, and almost no property qualifications (those were abolished in the wake of Shays' Rebellion). Nothing like that broad a franchise had ever been known before in history.
It's kind of silly to claim that either Rome or Athens were genuine democracies.