Sure they did. Read the debates in the Constitutional Convention. But first consider this.
In July, 1785, John Adams wrote to Thomas Jefferson several letters. In the first he mentioned a treaty of commerce between the US and England.
“I have given to Lord Carmarthen long ago, an Explanation of the power of Congress to form Treaties of Commerce…”
In a second letter about a treaty of commerce with England, Adams wrote,
““The Britons alliens Duty is a very burthensome Thing, and they may carry it hereafter as far upon Tobacco, Rice Indigo and twenty other Things, as they do now upon oil. to obviate this, I think of Substituting, the Words “natural born Citizens of the United States,” and “natural born Subjects of Great Britain,” instead of “the most favoured Nation.””
On April 4th, 1786, Adams and Jefferson submitted a draft treaty of commerce to Lord Carmarthen,
“My Lord
Agreably to your Lordships request expressed to one of us in Conversation, and again communicated to us through Mr. Fraser, we have drawn up the enclosed Project of a Treaty of Commerce, which we do ourselves the Honour to propose to the Consideration of his Majesty’s Ministers.
We have the honor to be
J Adams T: Jefferson“
The treaty has this clause:
“The Subjects of His Britannic Majesty may frequent all the Coasts and Countries Bay’s, Harbours, Creeks, Rivers and Ports of the United States of America, and reside and trade there, in all Sorts of Produce, Manufactures, and Merchandize, and Shall pay within the said United States, no other or greater Duties, Charges, or fees whatsoever than the natural born Citizens of the United States themselves are or shall be obliged to pay; and they shall enjoy all the Rights, Priviledges, and Exemptions in trade Navigation and Commerce which the natural born Citizens of the said United States do or shall enjoy.”
Article 3 of the treaty had this clause:
“…only as are or shall be paid by the natural-born subjects of Great Britain, in the Dominions of His Britannic Majesty, and the natural born Citizens of the said United States within their Dominions.”
Who were the natural born citizens of the United States in 1786?
It took me awhile to grasp where you were going with this, but now I think I understand what your point is. You are saying that references to "natural born citizens" of the US in 1785 and 1786 constitute evidence that they considered themselves to be "natural born citizens" at that time, and therefore the notion that "natural born citizens" could only be those born after July 4, 1776, is wrong.
I can see where you get the idea that these quotes support your claim, but your claim is not the only possible explanation for why someone would have made such statements.
My first thought is that the writers were not looking at the issue from a specifically legal technicality perspective and were careless in the usage of such terms.
The reason I think this is the case is because of what the constitution specifically says.
"or a Citizen of the United States, at the time of the Adoption of this Constitution,"
Well the Constitution was written in 1787, and so the only "natural born" citizens would be at most 11 years old, so clearly they weren't referring to these.
Could they have been referring to immigrants? People who came to the US between 1776 and 1787?
Well that doesn't make any sense, because immigrants is explicitly the class excluded by the "natural born citizen" clause.
If it refers to everybody in the US, then the qualification of " or a Citizen of the United States, at the time of the Adoption of this Constitution, doesn't make any sense, because everybody is already a "natural born citizen."
The *ONLY* explanation for those words that make any sense is if people born as "natural born subjects" become citizens in 1776. Indeed, the Supreme court holds that US citizenship begins July 4, 1776. (Inglis vs Sailor's Snug Harbor, if I recall correctly.)
I think Adams, Jefferson and others used that term of art in an effort to avoid having to provide a complicated explanation of the distinction between "subject" and "citizen", and were more interested in conveying the idea to the English using terms which the English could understand in their own way.