This nation is a representitive republic, not democracy, has been since the begining. The folks over at Hilsdale college have a free online course where you can educate yourself.
Yes. it’s a republic. It’s a representative democracy.
Many republics are dictatorships. Several non-republics are representative democracies.
Great Britain is a representative democracy, but is a monarchy.
Iran is a representative democracy but is a theocracy.
You need to learn the difference between how laws are made and the basis of the laws.