The founders themselves made a distinction between a mere citizen and a natural born citizen in the same sentence of the Constitution IE "No person except a natural born Citizen, or a Citizen of the United States, at the time of the Adoption of this Constitution, shall be eligible to the Office of President; neither shall any Person be eligible to that Office who shall not have attained to the Age of thirty-five Years, and been fourteen Years a Resident within the United States.
Wong Kim Ark only deals with citizenship. Mr. Ark is NOT a "Natural Born" Citizen, neither is BHO, and NO court has ever said they are!
They had to make that distinction because at the time of ratification, no one would have qualified as a natural born citizen of sufficient age to be president, so they may an “initial condition” exception.
Yes, as you said, there IS a distinction between “natural born citizen” and “US Citizen”.
Now, if concern troll wants to say that we should ignore this qualification, go for it. State that the Constitution’s requirements and restrictions shouldn’t be adhered to today.
The court ruled that he was a citizen by birth, i.e. a natural born citizen.