Libhater posts a youtuber, wonderful, there are plenty of youtubers claiming America is a democracy and a republic, or republic and not a democracy, or neither, take your pick.
I'll go with Merriam-Webster AND Encyclopedia Britannica, and the Gov's own website, all of which state that America is both a Republic and a Representative democracy.
Democracy - Factions, Parties, Politics: In many of the city-state democracies and republics, part of the answer to question 3—What political institutions are necessary for governing?—consisted of “factions,” including both informal groups and organized political parties. Much later...
www.britannica.com
And which is the United States?
www.merriam-webster.com
A democracy is most often a type of republic that elects it's leaders, either directly or indirectly, and the terms are not mutually exclusive.
A republic can be a nation of either elected or appointed leaders, as opposed to monarchy where leadership is inherited, so republic is the broader term and 'representative democracy' qualifies it even further. America is both a representative democracy and a constitutional republic.
So says Merriam-Webster
So says Encyclopedia Britannica
So says the US Government