The U.S. is a democracy. But don't take it from me. Take it from USCIS, which publishes a 9-page pamphlet, written in plain English, to acquaint immigrants and newly-naturalized citizens with our system of government. I have posted page 1 above, which references the word "democracy" 4 times.
https://www.uscis.gov/system/files_force/USCIS/files/Government_and_You_handouts.pdf?
And here's a link to a longer, 33-page guide which defines the U.S. as a "representative democracy" and includes the word "democracy" 13 times.
https://www.uscis.gov/sites/default/files/USCIS/Office%20of%20Citizenship/Citizenship%20Resource%20Center%20Site/Publications/PDFs/M-638_red.pdf
The 33-page guide also includes the word "republican" or "republic" 11 times.
How is that possible?!?!?! You might ask. Are the "Leftist," bureaucratic authors of this guide confused and ignorant of civics?
Or... Could it simply be that "democracy" and "republic" are not exclusive terms?
Side-note: Of those 11 usages of the word "Republic" in the 33-page guide, 6 are in direct reference to either the Democratic-Republican Party of early U.S. History, or the modern Republican Party. (Not to the fact that America is a republic, although it is also that, as well.)
And 1 of those 11 references is to the USSR: the Union of Soviet Socialist Republics!