I think I am going to take the word of Constitutional scholar like David Ramsay, who wrote in 1789:
"The citizenship of no man could be previous to the declaration of independence, and, as a natural right, belongs to none but those who have been born of citizens since the 4th of July, 1776."
But he's clearly wrong about that. I mean, that's not the law in the U.S. as of today. Because even if you buy De Vattal's argument, that still leaves a potential 14th amendment argument.
Let's assume Ramsay's right. As of 1789, you can either be a born as a citizen, of become a citizen after birth. And as of 1789, the only way you could be born a citizen is if both your parents were citizens when you were born. Because De Vattal doesn't recognize jus solis citizenship at all. To him, it doesn't exist.
But it does exist after the 14th Amendment. Now, did the 14th amendment create a third class of citizenship, or did it just modify the meaning of what constituted an NBC, living in place that clause's distinction between those who were citizens at birth, and those who were naturalized?