I'm certain the founders didn't invent the term "natural born" on the fly.
Has anyone done an analysis of surviving period literature; Colonial, American, British and French to determine what "natural born" was understood to mean at the time?
That is part of what is underlying my discussion and some of the articles and briefs out there and in the works. It certainly would be part of any review conducted by the SCOTUS.
Any analysis must start with the framers’ intent, which clearly, according to the literature they created at the time, was to ensure that usurpers could not become President and, therefore, Commander in Chief. They were focused on limiting the office, so far as possible, to those who did not have foreign allegiance-—which, especially at the time, meant foreign citizenship. Since citizenship was passed by birth (by descent), the only way to accomplish their goal was to limit the presidency to those with American parents (or father, if at the time that was the parent who passed citizenship).
Effectively, the “natural born citizen” standard limited the presidency to those who were at least second-generation Americans.
A child born to a British subject, particularly a British father, would not be a second-generation American on his father’s side.