Shutter speed is the camera setting that controls how long the shutter opens and closes, affecting how motion is captured.
This photo is interesting to me is because of not only the difference in scale with the people and having this many people at the same time, all blurred out and meshing with each other.
This photo does have a good contrast of scale with the person closest to the camera appearing noticeably largest than the person farthest away from the camera. The geometry of the stairs and the railings creates strong leading lines as well.