Complex sentence: William F. Mangels (1866--1958), amusement manufacturer and inventor, worked at Coney Island and was a major player in the development of American amusement parks at the start of the 20th century.
Split into simpler sentences: William F. Mangels (1866--1958) was an amusement manufacturer and inventor. He worked at Coney Island and was a major player in the development of American amusement parks at the start of the 20th century.