Sorry for your deficiencies in education, but that is what a REPUBLIC is. The founders did not create a new NATION, they created a common government. The states were not destroyed, by states they acceded to a common government, and to that new government they DELEGATED certain powers - for enumerated puposes. Delegated powers can be resumed.
The Constitutional Convention was authorized by the Congress of the United States. States had nothing to say about it.
States were the parties in CONGRESS. And per their existing agreement - the Articles of Confederation & Peretual Union - such changes required UNANIMOUS consent per Article XIII - yet only 12 states attended, two members of the New York delegation left in disgust leaving that state without a vote in convention, and the NEW government was created when 9 - NINE - states ratified. I don't know about math in yankee states, but here in the South, 9 is less than 13.
The Continental Congress created the states and nothing you say can change that. They are subordinate units of our Nation.