In many ways your 1776 was downstream of our 1688 which essentially established the English constitutional system and our bill of rights. Only in the English system parliament was considered sovereign as it represented everyone including the crown and the church. In the US system the constitution was considered sovereign.

Essentially the real mistake of both systems is personality matters more than words on a page. In 1997 the labour government here essentially gutted our "constitution" that while not written had been a long established way of doing things. Tony Blair created a number of new bodies outside of parliamentary control filled with friends of his who have essentially left us in a state of perpetual constitutional crisis. We have a "supreme court" since 2009 filled with left wing activist judges who make insane rulings often vetoing legislation passed by parliament. Something that simply was not a thing in the 1980's for example. The supreme court will make insane rulings and we are told that is the end of it even though my car is older than the supreme court.

Our constitution was subverted from within by our political class because it was unwritten but I have seen no evidence than the US has been any more resilient to this. It's essentially been done by the civil rights act and the national security state and by activist prosecutors and courts in certain jurisdictions like Southern Virginia, New York and Austin.

In my opinion the insulating factor that has slowed down the process in the US compared to the UK is that in a federal country power is more diffuse than in a unitary state. You have extra layers of competing interests with federal, state, county and local. The federal system also provides some kind of insulation in the event of a collapse of the federal system, administration can be devolved to a more local level. The British state has become very overly centralised since the second world war. The breakdown of the state would have serious consequences here.