I stait up quoted the constitution of the United States and you are still trying to argue.
Section 2:
The House of Representatives shall be composed of Members chosen every second Year by the People of the several States, and the Electors in each State shall have the Qualifications requisite for Electors of the most numerous Branch of the State Legislature.
The constitution doesn't need to say, "representative democracy", if it functions just the same via the words "the People will elect their representatives to carry out their (our) will." That is, by definition, a representative democracy.