It's your assertion that the colonies were inseparable, and operated as a unit. Check the date of independence for Rhode Island & Providence Plantations (4 May 1776), Deleware (15 Jun 1776), New York (9 July 1776). The signing of the Declaration wasn't even complete until August. Despite a federal congress, the states were sovereign.
That's not even close. My assertion is that the representatives of the independent-minded colonists, acting jointly as the Continental Congress, formed a Union known as the United States. It has been a Union ever since.