So contrary to popular belief, the "Founders" were not the main proponents of separation from Great Britain -- quite the contrary. Most Founders were quite hesitant to pull away. However, populist movements really started to become prevalent by the end of the 1760s.

To explain, Founders like John Adams had a long history of fearing Democracy and many other aspects of their future government. Check out Adams' own early view of democracy in 1763:

Democracy, will soon degenerate into an Anarchy, such an Anarchy that every Man will do what is right in his own Eyes, and no Mans life or Property or Reputation or Liberty will be secure and every one of these will soon mould itself into a system of subordination of all the moral Virtues, and Intellectual Abilities, all the Powers of Wealth, Beauty, Wit, and Science, to the wanton Pleasures, the capricious Will, and the execrable Cruelty of one or a very few.

Yeah, not very flattering, is it? However, his views eventually evolved as the situation in America became more severe.

By the early 1770s, populist movements across America really shifted American politics as a whole. Books like Marjoleine Kars' Breaking Loose Together: The Regulator Rebellion in Pre-revolutionary North Carolina outlines the ways that populist movements in the South were able to fight back against corruption and the government (mainly between 1766 - 1771). This is important because "Regulator Rebellions" had a direct impact on what happened after the war.

Between 1772 - 1775, a lot changed, and most was spurned on by the general public. Everyone knows about the Boston Tea party, but most people don't realize that the Boston Tea Party caused a ripple affect with Tea Parties all across America in 1774. Tea Parties happened in many American cities, including Philadelphia, Annapolis, Charleston, and many others. This forced the gentry into a precarious situation. Some, like Charles Carroll of Carrolton corresponded with his father about this in 1774, essentially saying that while he doesn't think that these protests are a good thing, the rich and powerful must get involved in American politics so they can secure their place in America's future.

That's why the tone of the early Continental Congress is very tame. Internal proceedings show that many states, especially in the South, leaders were not keen to even consider separation from Great Britain. But the challenge was that as the Continental Congresses met, the people back home kept protesting, and burning down the houses of tax collectors, or kicking governors out of their homes. A great book that tackles this is Terry Bouton's Taming Democracy: The People, The Founders, and the Troubling End of the American Revolution where he correctly ascribes many of the Founders to be hesitant leaders towards independence. It also explains why, even after minor hostilities broke out in 1775, the Founders still sent the "Olive Branch Petition" back to Britain as they vainly hoped to stop a full war before it happened. Even when the Continental Congress empowered General George Washington with command in June 1775, they did not expect that his duties would necessarily be a full-break with Great Britain. The Continental Congress wanted some autonomy from Great Britain and some representation in government, which they believed was more achievable than independence.

Now I should disclaim that this isn't true of all Founders. Some, especially in the North were much more pro-separation than many others. Samuel Adams, who was very vocal and active during the Stamp Acts protests, helped organized the Boston Tea Party, and was a member of the Continental Congress Representing Massachusetts was very vocal from the beginning that he believed separation from Great Britain should be a primary goal. There are a few others that fall into this category, but not many.

Tl;Dr: Most founders dragged their feet as the American "mob" dragged them forward .

Edit: fixed a misspelled name.