We are going to have to disagree on the notion that the people who wrote what could be two of the three most radical documents in the history of Western civilization (Declaration of Independence, The Constitution, The Magna Carta) were conservatives.
Heck Luis, we can't agree on everything...
The Magna Carta was designed to end rebellions and try to create a better balance between crown and people. It wasn't the first of its kind, but probably the most important for a few centuries, though it didn't ultimately stop a revolution in England.
The Declaration of Independence was designed to start a rebellion because that balance between crown and colonies had deteriorated.
The Constitution was simply an attempt to improve on the Articles of Confederation, which in the latter case was designed to bring the colonies into a legitimate form of government.
All three were attempts at defining the role of government and where the liberty of its people were formally outlined. Radical yes. But did set standards for a conservative philosophy.
Which did not exist prior to the American Revolution. It's hard to conserve something that didn't exist before you.
The term didn't define the philosophy. What Burke did (while justifying a monarchy) was to bring words and meanings people could understand to the principle that a government can coexist with its people, who have undeniable rights, and each having a responsibility to that coexistence.
A conservative will do everything reasonable to maintain that important balance, but is not above using radical avenues to do so. IMHO. Real radicalism today is designed to diminish that balance.