Wilfred Reilly at Quillette patiently explains to the NYT that there was no USA until 1776 - and not even then. Not yet.
It's grade school information: The colonies were British colonies, each separately governed by Brit governors beholden to London. Just like Brit colonies all over the world.
Unification, and rebellion, was extremely difficult requiring all sorts of compromises. Some ugly, some wonderful and wise.