I agree: “Subject to the Jurisdiction” of the United States” means exclusively only what Congress has passed laws establishing its jurisdiction for purposes of citizenship.
There are two kinds of “Birthright Citizenship”: Citizenship bestowed by the state and citizenship bestowed as a natural right. Citizenship bestowed by positive law is naturalization. Citizenship bestowed by citizen-parent(s) is natural citizenship.
Birthright citizenship
Too many people give too much deference to the "courts."
The Courts got steered wrong by William Rawle, and they have never recovered from the damage.