Your opinion is wrong by definition. A Democracy is simply rule by the people and a Representative Republic is a form of Democracy.
Rome was also a Representative Republic, but one which limited the authority of the Comitia (people’s assembly). All power rested in the Senate - which only the wealthy elites could run for. The Consul and Religious leaders could only be elected/appointed from the Senate.
The American Republic limits the power of the people by giving each state, regardless of size or population, 2 senators. But the USA is still a democracy.
Right wingers keep pretending that the US isn’t a democracy, as justification for their anti democratic policies of voter suppression and gerrymandering.
A republic is a form of democracy, in which representatives are elected, as opposed to direct democracy where everyone votes on every question.
Canada has Constitutional Monarchy which is another form of democracy. All democracies have a constitution. The USA is no different than any other Democratic country in the world in that regard.