The concept of ‘natural born citizen’ was obviously known to the Founders; but is there anything in their other writings explaining exactly what they meant by it? (not Vattel.)
Yes, Letters between the founders explaining why it was important. But that will not save the Nation. The truth has no traction on this issue.
Some of that evidence is enumerated in this thread
https://freerepublic.com/focus/f-news/2840767/posts
https://www.art2superpac.com/issues.html#Constitutional%20Convention
https://puzo1.blogspot.com/2015/03/a-response-to-neil-katyal-and-paul.html