Short answers, pulled from the story.
Running is a method of terrestrial locomotion by which humans and other animals move quickly on foot. It is a gait with an aerial phase in which all feet are above the ground, unlike walking, where at least one foot always stays in contact with the ground and the legs are kept mostly straight.
It is hypothesized that the ancestors of humankind developed the ability to run long distances about 2.6 million years ago, probably to hunt animals. Human running itself is thought to have evolved at least four and a half million years ago out of the ability of Australopithecus to walk upright on two legs.
The Tailteann Games, an Irish festival in honor of the goddess Tailtiu, date back to 1829 BCE and rank among the earliest records of competitive running. The first recorded Olympic Games took place in 776 BCE, and running in Ancient Greece can be traced to those games.
Heel striking is generally associated with higher rates of injury because pressure travels through bone rather than muscle for shock absorption. Bones cannot disperse forces easily, so the load passes into ligaments, joints, and bones up to the lower back, while a mid or forefoot strike absorbs force through the triceps surae acting as a muscular lever.
Running is associated with improved health and life expectancy, including weight loss, improved cardiovascular and respiratory health, reduced total blood cholesterol, stronger bones, and better self-esteem. People who have already had a heart attack are 20% less likely to develop serious heart problems if they run or do other aerobic activity more frequently.
The fastest human footspeed on record is 44.7 km/h, recorded by Usain Bolt as the average speed between the 60th and 80th metre of a 100-metre sprint.
Running events include track running on an oval, road running on measured road courses, and cross country running over open or rough terrain. There is also vertical running, which covers natural-feature events like fell, trail, skyrunning, and mountain running, and structure-based tower running up buildings such as the Eiffel Tower or Empire State Building.