Complex sentence: Before the appearance of the starter motor, engines were started by various difficult and dangerous methods, including wind-up springs, gunpowder cylinders, and human-powered techniques such as a removable hand-crank.
Split into simpler sentences: Before the appearance of the starter motor, engines were started by various difficult and dangerous methods. Some of these methods includes wind-up springs, gunpowder cylinders, and human-powered techniques such as a removable hand-crank.