At any rate, what the founders actually did, that's in the constitution. Art IV, Sec. 2, 14th amendment, and a power to Congress to makes of naturalization. There is a body of law outside the constitution, more like legal principles (constitution is superior to a statute, due process includes you get to tell your side); and citizenship law between nations is one such body of ancient law. This body of law is WELL KNOWN, to lawyers.
Here’s a question your position can’t answer:
If the Constitution writers settled NBC as you say, and only naturalization was left to Congress (as if the two can be considered entirely separately) then why wasn’t the Naturalization Act of 1790 either challenged or even described as Unconstitutional? Why wasn’t it Unconstitutional for Congress to define NBC, and especially as it did?