If we were a democracy (which we aren’t) then we would collectively decide our own laws and policies. But we don’t do that. We vote for “representatives” who do such voting in our name (allegedly).
Therefore some people make the mistake (and it is a mistake) of trying to label us a “representative democracy.” That, too, is a false label because if it were accurate, then the representatives could vote for any bill or policy they wished. But they can’t.
Why not? Well, obviously, they are explicitly prohibited from doing so, in many cases, and implicitly prevented from doing so, in other cases. How? Our Constitution set things up that way. It establishes not only the specific things over which our government HAS authority but also denies them authority in a variety of other matters.
This is why we are not a democracy. Our Founders and Framers were very well aware of a tyranny of any (temporary) majority. They also mistrusted the power of government in general. So, they deliberately avoided “democracy” and further limited the things over which the government had authority. We are a Constitutional republic.
Like people are in general, our Constitution is indeed imperfect. But it is vastly superior to the other forms of government. And, it is designed to make it within our collective power to modify it to address any perceived deficiencies in our form of government, as we see fit.
So whenever any of our detractors attempt to tell us that we are a “democracy,” we owe it to ourselves to correct them. Stop the spread of their disinformation. We are absolutely not a “democracy,” thank God and thank the Framers.