No they didn't.
The exception clause is written for that generation only. There was no United States until the Constitution was adopted so, ipso facto, not a single signatory (nor anyone else above infancy) would be qualified without that clause. I, for one, am happy that George Washington got a chance to serve since he was born a British subject.
Here is the applicable clause from the Constitution.
No person except a natural born Citizen, or a Citizen of the United States, at the time of the Adoption of this Constitution, shall be eligible to the Office of President; neither shall any Person be eligible to that Office who shall not have attained to the Age of thirty-five Years, and been fourteen Years a Resident within the United States.I pasted that from a marvelous .pdf I found. It downloads quickly and allows you to run word searches for things like 'natural' 'born' 'naturalized' etc.
Based on this, would Bobby Jindal be eligible for President? Marco Rubio? Looks like it to me...
You poor thing, you just posted the very sentence which shows the founders differentiated mere citizen from natural born citizen ... if there were no difference, why address two separate types of citizen while not yet addressing naturalization? But keep on trying to shove your square peg barry bassturd into the round hole. It is instructive for readers.
That's a unique claim you've made. Are you suggesting that the title of the document we call he Declaration of Independence is incorrect? You do know the title of that document, don't you? Here, I'll help you out - its real title is:
The Unanimous Declaration of the thirteen united States of America.
IOW, we were the united States of America before the Constitution was written. The men who would be leaders at the adoption of the Constitution were citizens before the adoption of the Constitution. That's the plain meaning of the NBC clause.
A person could meet the requirements of that clause one of two ways: By being a person who was a citizen at the adoption of the Constitution, or being a citizen who was a Natural Born Citizen in the next generation.
That must mean there is a difference between being a citizen and being a Natural Born Citizen. That is the plain meaning of the clause. To disagree with that is silliness. There is a distinction and a difference between the two citizenship classes or it wouldn't have been necessary to make the distinction.