How was the American Revolution not a revolution?
One can argue that the American Revolution was not a revolution because it did not fundamentally change the social or even the political system of the American colonies.
Before the Revolution, the colonies were a fairly egalitarian society that was based on free enterprise and had a fair degree of democracy. After the Revolution, nothing changed in a qualitative or revolutionary way. America was still egalitarian, though it was perhaps more so after the Revolution. It was still based on free enterprise. America was more democratic after the Revolution, but the change was not huge.
Essentially, the Revolution (one can argue) caused a change at the top of the American system, substituting American elites for British elites. Meanwhile, the system as a whole was not markedly different from that which existed before the Revolution.