-Louis Freeh, FBI Director, 1997
Getting at the philosophy of the time, they came from a society where a King declared that he was the true and proper ruler by divine providence and that his government was legitimate because he (as an agent of God) said so.
Divine right had been cast down centuries before by the Magna Carta, and George III was not a particularly powerful monarch. The many grievances expressed by the American colonies in the Declaration of Independence were in fact perpetrated by Parliament. Yes, an elective representative body was responsible for trampling the rights of the colonists. The members of the Continental Congresses knew this, and they also believed true power lay in the legislative branch. That's why the Bill of Rights says "Congress shall not..." rather than "government shall not..." Our courts and our society (so far) have decided that the Bill of Rights does indeed apply to all three branches of government and to the state governments.