Why a pulley changes the pull
Pro-Tip. Count the ropes holding the load. More ropes, less pull.
A pulley is a grooved wheel the rope turns on. It does not make energy. It trades how hard you pull for how much rope you haul.
A fixed pulley is bolted to the beam. You pull down and the load goes up. One part of the rope holds the load, so you still pull the full weight. The wheel only changes direction.
A movable pulley rises with the load. Two parts of the rope hold it, so you pull about half the weight and take in about two feet of rope for each foot the load rises. Count the vertical parts that support the load. Do not count the free end you are pulling if it leaves a fixed wheel. Four supporting parts means about one fourth of the weight, and about four feet of rope.
Worked example
A 200 lb load hangs on two supporting rope parts.
Pull about 100 lb. Haul 2 feet of rope to raise the load 1 foot.