In the United States of America one can be a citizen, by birth or naturalization.
Add the adjective born to citizen, and that eliminates naturalized citizens.
Add the adjective natural to born citizen, and we now have a third classification obviously different than a born citizen.
The definition is found in The Law Of Nations or PRINCIPLES OF THE LAW OF NATURE APPLIED TO THE CONDUCT AND AFFAIRS OF NATIONS AND SOVEREIGN.
Many of our Founders were fluent in French and were intimately familiar with Emmerich de Vattel’s work. They used quotes and ideas throughout the Declaration of Independence and the united States Constitution.
The term natural born citizen was known and understood as one who is born with jus soli AND jus sanguinis. In fact a draft of the USC was changed to natural born citizen from native citizen to insure the office of Commander-in-Chief would never be held by anyone with foreign allegiances.
Natural born citizen is one who is born in the United States of America to two parents who are themselves citizens of the United States thus maintaining the Commander of all military forces have total allegiance to no other nation than the U.S.A. for obvious reasons.
The exception clause; “or a Citizen of the United States, at the time of the Adoption of this Constitution,” was necessary since a President would not be able to hold office until the Original Citizens (those that twice swore an oath of allegiance to the USA) had children that reached the age of thirty-five years old.
This requirement was not necessary for the Congress. Original Citizens could hold office in the Congress if they swore an oath when the Revolutionary War began (the Senate) or before it ended (the House).
This is an accurate historical analysis of the origins of natural born citizen used in our Constitution as one of three requirements to hold the office of President of the united States and Commander-in-Chief of all U.S. military forces taken from the writings of the Framers of our Constitution and the Founders of our nation.
You may accept these facts as true or not. That is your choice.