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?
The words of the 1790 Act are not a definition, even though it's popular to think so, and even though the Senate claimed it was, etc.
The phrase that appear in there is "shall be considered as." This operates to create a legal fiction. A couple examples, to show that this is not a definition. It wasn't a definition in 1790, and it isn't now.
"X shall be considered as Y" means "X is not Y, but we will pretend it is."
There is a US regulation on social security, 20 CFR 416.1856. Who is considered a child. It says that if you are under 22 years old, you will considered a child. That is not a definition that a 21 year old is a child. It is a statement that the law will pretend they are a child, until they are 22 years old.
It was unconstitutional for the 1st Congress to define NBC in a statute, certainly to a birth abroad. The constitutionality was never tested, how often do we get a mix of election and an unqualified candidate? The law was repealed in 1795. Somebody probably figured out that what was done in 1790 was unconstitutional, and rather than test it in court, they got rid of it.
Here is another thought for you. Cuba has a statute that is similar to the US. When Ted was born, on his birthday, Cuba had the same claim on Ted that the US did. Born abroad of one citizen parent. Mom was US, Dad was Cuba, both countries automatically attach citizenship at birth. Now, the law looks at the birthday, and stops. It can't predict how the human's life will proceed.
The Framers in Article II distinguished between a “citizen” and a “natural born citizen”. The first Congress, many members of which were Framers, in the Naturalization Act of 1790 distinguished between a “citizen” and a “natural born citizen”.
In the Naturalization Act of 1790 the distinguishing characteristic between persons naturalized with a status of “citizen” and those naturalized with a status of “natural born citizen” was parental US citizenship.
Congress in the Naturalization Act of 1795, et seq, no longer made such a distinction and declared all such persons naturalized to be “citizen”.
Are we to conclude that subsequent to 1795 there were no further “natural born citizens”? They ceased to exist? Or are we to conclude that other children born with parental US citizenship - those who were not “born beyond Sea, or out of the limits of the United States” - those born within the United States - are “natural born citizens”? Or are these other children - born with parental US citizenship within the United States - something other than “natural born citizens”? Was it necessary that they be “born beyond Sea, or out of the limits of the United States” for them to be “natural born citizens”?
The only rational conclusion is that those born within the United States with parental US citizenship are “natural born citizens”, and all others are not.
The 1790 Act et seq. also demonstrates that the foreign-born children of citizens have always required naturalization. The 1790 Act provided a legal fiction that some naturalized persons be “considered as” natural born citizens, not that they are natural born citizens.