First off, the first draft of the Declaration of Independence was submitted to the Continental Congress on June 28, and they fiddled with it for a few days making some changes that Jefferson didn't really much like. They finally voted on the idea of Independence on July 2, and that's the date that most people thought would be celebrated in the future.
Interestingly, most colonies early on didn't particularly want to rebel or form a "more perfect union," but rather wanted to get more rights and have their grievances addressed by the King. It was Thomas Paine who wrote Common Sense in 1776 and got people fired up over independence. John Adams said that without it, the "sword of Washington would have been raised in vain." Paine made a habit of inciting revolutions, as he moved to France and wrote Rights of Man in 1791, which had the distinction of also fomenting the proletariat, and then getting him thrown into jail by Robespierre.
Jefferson had to take out some stuff about slavery because the Southern representatives were pissed off about it. An original draft read, "he has waged cruel war against human nature itself, violating its most sacred rights
Jefferson was guilty of plagiarism, probably. But it's ok. Everyone copied stuff back then. George Mason was a representative to the Virginia convention in 1776, and in June he published The Rights of Man, which starts off, "THAT all men are by nature equally free and independent, and have certain inherent rights, of which, when they enter into a state of society, they cannot, by any compact, deprive or divest their posterity; namely, the enjoyment of life and liberty, with the means of acquiring and possessing property, and pursuing and obtaining happiness and safety."
Richard Stockton, a lawyer from Princeton, recanted a year after signing the Declaration of Independence. He was captured by the British, thrown in jail, and wound up recanting and swearing an oath of allegiance to King George.
Random weirdness - both Jefferson and Adams died on July 4, 1826, exactly 50 years after the Declaration was adopted. That's spooky.