The legal meaning of Natural Born is NOT one who is born in the US (only).
Natural born is “a citizen by natural operation of law.
One who does not need to be Naturalized (”Made as if Natural”) by operation of statutory law.
A “natural born” citizen’s parents are both citizens at the time of birth. The issue that gave rise to the term was allegience to the country.
A person born here to non-citizen parents can only be a citizen if those parents were here under a resident alien visa, and thus having surrendered to the laws of the United States, IOW, there is no such thing as an “anchor baby.”