The Plymouth colony was ruled by a Governor some of the earliest Governors were John Carver, William Bradford, and Edward Winslow. The people that had the power were full citizens or called "Free Men". To be a Free Man at the beginning of Plymouth colony you had to be sponsored by an existing Free Man and be accepted by the General Court. Later the colonists changed it so a Quaker couldn't become a Free Man and they made an age limit in between the ages of 21 and 40. A Free Man could vote and run for Governor.
From "Plymouth Colony." en.wiki.org/wiki/Plymouth_Colony