You’re misunderstanding the part about saying being born since the Revolution. Those children whose parents adhered to U.S. loyalty were recognized as U.S. citizens and those who adhered to British loyalty were recognized as British subjects. Had McClure been born before the Revolution, then it wouldn’t have mattered because there were different rules in effect prior. You also seem to be missing the part of what you quoted that says “agreeable to the laws and usage of the United States” ... IOW, U.S. law has to be considered and not English common law which most Obots think is what makes birth on U.S. soil sufficient to be a natural born citizen. The SCOTUS said it’s not ... and several times over.
It’s quite clear.
James McClure was born on US soil SINCE the Revolution.
Such fact, without any regard at all as to the citizenship of his parents, made him a US citizen.
In fact, it made him a natural born US citizen.
You’re right that there was a different rule shortly before the Revolution. If a person was born in the United States shortly before the Revolution, and his parents carried him back to Britain, they had chosen British citizenship for themselves and for their children. If that child didn’t act promptly to return to the United States upon reaching adulthood, he was deemed to have accepted that adoption of British citizenship. But he had a right to return to the United States and take up American citizenship (if he made that choice promptly) because he was born here.