The three individual words do, the collective term of art does not. I have long pointed out the mistake of interpreting it in accordance with the meaning of the individual words vs interpreting it in light of the origins of the term and it's context as used by the founders. In the same manner that "freedom of speech" and "freedom of press" goes way beyond just the meaning of those words, just so does the meaning of "natural born citizen" transcend the addition of words put together. In the context of article II, it means born as a "natural citizen."
In the absence of congressional statutes, who was a U.S. citizen at birth would be determined based on the common law.
Not trying to nitpick, but at the time of the Constitution's ratification, who would be a citizen was determined by each individual state and whatever happened to be their law on the subject. (Note, this particular law, written by Thomas Jefferson, denies citizenship to the children of aliens unless their parents become citizens.) In the absence of such laws, courts would harken back to "common law" as a matter of procedure, not necessarily because it was correct. Lynch v Clarke is an example of where the court did this, and the applicability of their ruling was subsequently overturned by the action of the New York Legislature. This particular sub-topic also highlights the difference between what is a citizen for the purpose of being a citizen of a state, and what is the requirement for being a citizen of the Nation itself. In 1787, there were no uniform requirements from state to state. Article II and the subsequent naturalization act of 1790 are the closest things of which I know to attempt to define it regarding Federal citizenship.
However, the common law is determinative only when the legislature has not adopted a specific statute on the subject matter.
But only because the Court system chooses to do it that way. It is another example of their habit of asserting "precedent" as opposed to first principles. Everyone must acknowledge that English laws regarding "subjects" were overturned in the two wars we fought with them over the issue. Why the courts insist on looking to laws regarding "subjects" which we through off in two wars, is simply because they were convenient "precedent."
In the 1790 statute, Congress provided that the foreign-born children of U.S. citizens were U.S. citizens at birth so long as the parents had resided in the U.S. at some point. While it is not clear who would be a U.S. citizen at birth under common law (the Happersett Court noted that some authorities maintained that the position that only the U.S.-born children of two U.S. citizens would be citizens at birth under common law was incorrect, and the Court did not rule on the matter, since it was unnecessary for the disposition of the case), since 1790 the foreign-born children of U.S. citizens (with certain limitations) have been citizens at birth, and since at least the adoption of the 14th Amendment all children born in the U.S. and “subject to the jurisdiction thereof” (which I believe should exclude children of illegal aliens, but all three branches of government understand to include even them) are U.S. citizens at birth.
If your "citizen at birth= natural born citizen" theory was correct, Aldo Mario Bellei would not have lost his citizenship for having failed to meet residency requirements. He was a "citizen at birth" but he was stripped of his citizenship. A "natural born citizen" or a "born" "natural citizen" (as I like to make it clearer) cannot be deprived of their citizenship for failing to meet residency requirements. Clearly there is not equivalence to "citizen at birth" and the meaning of born a "natural citizen."
If you don’t believe me that a U.S.-born child of two permanent residents is a citizen at birth, try to bring an application for naturalization for such a person and see what the courts say.
A point I constantly harp on is that "what the courts say" is not proof that something is true or not. The Courts got Roe v Wade wrong, they got Kelo v New London wrong, They got Wong Kim Ark Wrong, and it took them over two hundred years to get McDonald v Chicago right! That THEY don't even know what they are talking about is demonstrated by the fact that so many court decisions are split. If they can't even manage to find unanimity, how much faith should we put in the accuracy of their opinions?
Given our disagreement on the meaning of “natural-born citizen,” I think that we are likely to continue to talk past each other in this debate, and will have to agree to disagree on the constitutional eligibility of a citizen at birth who does not have two citizen parents or who was not born in the U.S.
But I did want to point out that the law by which Bellei claimed U.S. citizenship did not provide that he was a birthright citizen ipso facto his birth to parents who had met certain citizenship and prior-residency requirements, but affirmatively imposed a future residency requirement for such person. It is true that a natural-born citizen—someone who is a citizen by the mere fact of his birth—would not need to reside anywhere in order to be treated as a citizen, but that is an argument for recognizing that persons like Bellei, who needed to act affirmatively in order to continue to be treated as a U.S. citizen, were not natural-born citizens, and is not an argument for saying that persons who are U.S. citizens at birth without having to meet any future conditions are not natural-born citizens. So I would say that Bellei wouldn’t qualify as president even if he resided in the U.S. from the time he was a week old, since his citizenship didn’t really “vest” until some event took place after his birth. (And please note that the future residency requirement was a requirement to being recognized as a citizen henceforth, not merely a ministerial requirement for providing evidence of birth as a condition to being treated as a citizen, which requirement could be complied with through other means and failure to so comply would not cause the person to be stripped of his U.S. citizenship.)