If they were willing to ignore what they thought it means, as TJ did in my example why does it matter what they thought it means?
So what the folk who wrote it thought it meant doesn't matter. What you think it means trumps?
So why doesn't what Rosie O'Donut thinks the 2nd means trump?
BTW, note that in your own example, when TJ did something that he "wasn't sure" he actually had the authority to do, he said so, right there in his writings.
So where is the writings, where is any evidence at all, that anyone who was actually involved in the creation of the Constitution thought that the ordinary treatment of POW's at that time was unconstitutional?
For that matter, the Constitution itself is the best evidence that the various "god given" rights were not Universal in nature. As evidence, I refer you to the 3/5's rule--right there in the text of the Constitution. While that one was later revoked by Amendment (ah, those old days where, when people wanted to make a change to the Constitution, they actually passed an amendment rather than just "reinterpreting" it), those Amendments are specific in applying to US persons.