During the Colonial Period, what set up the basic system of government that is reflective throughout Colonial literature?
English law plus corporate charters.
American law, to this day, was and is based on English law tracing its roots to the Magna Carta.
Each of the 13 original colonies was founded as an English enterprise with a charter signed by the king. Within the charter were the basic laws of corporation and its purpose in the New World.
The colonists first set up their local governments, for example Boston in 1630 by John Winthrop, and then a colonial government was set up when multiple towns came into being. The magic date for Massachusetts is 1636 with just a few villages around Boston Harbor.