The Founders did not focus on the word “citizen”.
John Adams wrote the Massachusetts constitution of 1780 and used both terms “subjects of the Commonwealth” and “citizens of this Commonwealth”.
Massachusetts interchangeably used the terms natural born citizen and natural born subjects until 1791. In one 1790 act of naturalization they used both terms.
“John White, Roger Dickinson and John Atkinson (the said Atkinson in behalf of himself, his wife and children) ...”
“...become inlitled to all the rights and priviledges of natural born citizens”
“...shall be deemed adjudged and taken, to be free citizens of this Commonwealth, and intitled to all the liberties, priviledges, and immunities of natural born subjects.”
https://archives.lib.state.ma.us/handle/2452/104609
“...and still conducting themselves as the faithful subjects of our free Government, enjoy every temporal and spiritual felicity.”
President Washington’s letter to American Catholics, March 1790.
https://founders.archives.gov/documents/Washington/05-05-02-0193
1780.
What have you got from the 1760s?