There were many Loyalist living in the colonies before, during and after the Declaration of Independence and Revolutionary War. Most Loyalist were driven out of the country or imprisoned after the Revolutionary War.
Mary Washington was a Loyalist who remained in the Country. Consequently, colonial citizens were required to sign and state an Oath of Allegiance before they could become a citizen of the state.
Eventually, the various states united under the U.S. Constitution and citizens of the states became citizens of the United States. Consequently, the Founders made it a requirement that a person must be a citizen at the time of adoption of the U.S. Constitution or a Natural born citizen to become POTUS or VP.