You said:
Except that the “current operative interpretation of the 14th Amendment” is the interpretation of the Amendment that has governed for the vast majority of the time since the Amendment was passed.
And my answer is... So?
What does that matter? Truth is not defined by how common error is.
But the law is defined, in large part, by precedent. The Fourteenth Amendment, by its language, allows for birthright citizenship, subject to the requirement that the parents be subject to the jurisdiction of the United States. The “subject to the jurisdiction thereof” language was left undefined, and was first considered by the Supreme Court in US v. Wong Kim Ark (1898) - that’s the first authoritative statement construing the relevant language of the Fourteenth Amendment, and the Court pretty clearly laid out the basis for birthright citizenship, even where the parents are not themselves U.S. citizens.
We could argue for days over whether Wong Kim Ark was correctly decided - there are certainly arguments to be made on both sides (just as there were likely “framers” of the Fourteenth Amendment who believed different things about the breadth of the Amendment’s grant of birthright citizenship). But, at this point, 110 years later, the law is what it is.