The above video gives a great short lesson on how this is a Constitutional Republic, not a democracy, not an oligarchy, and certainly not a dictatorship.
i don't agree with everything said, such as the statement that dictatorships never really exist because in so-called dictatorships it is actually a small group who rule - which is an oligarchy. That may be true to some extent, but I think Hitler, Stalin, and Mao, for example, really did call the shots, with a loyal core cadre in agreement, rather than the small group deciding things with equal authority and then the dictator being merely the public face. That happens, but not always.
And certainly there will be libertarian anarchists who will disagree with the video's characterization of anarchy.
But it does give an excellent description of why this is not a democracy, which is something all too many Americans just don't get.
This is a Constitutional Republic, with the whole point being to secure and protect the pre-existing, unalienable rights of people. Those rights can be abused and violated by the one, the few, or the many and so a Constitutional Republic strives to shield those rights against all arbitrary power, including the power of the majority.
This is not rule by the majority, but rule by law, with the supreme law being a Constitution that intentionally divides and limits power, with a Bill of Rights added as an additional shield to protect you against the will of the majority or the will of powerful politicians.