The Founders made provision to alter their original thinking on any issue via the constitutional amendment process. They made it extremely difficult but not impossible to amend the Constitution.
One of the most important issues that the Founders and Framers debated and eventually compromised over was direct election of U.S. Senators. The Founders decided against it. The Founders decided that the House of Representatives would be popularly elected (democracy) and the Senate (from the Latin word “Senex” meaning “elder” or “wise old man”) would be indirectly elected by state legislatures (republicanism). However in 1913, the thinking of the Founders was changed by the 17th Amendment to the Constitution which provided for direct election of the U.S. Senators.
It is an analogous situation with the 14th Amendment which created only two forms of U.S. citizenship: born citizenship and naturalized citizenship. Since 1865, “Citizens of the United States at birth” and “natural born citizens” have been synonymous.
Yes, it's utter nonsense to think that the court which gave us "Separate But Equal", could have two different standards of citizenship.
(And the 14th amendment was passed in 1868, not 1865.)