From an evolutionary perspective, the utility of sports can be seen as a subset of play - sports are the adult version of childhood play.
They offer all of play’s benefits in stamina, speed, strength, and cognitive development, while also providing some of the skills early humans needed for hunting and battle.
Almost all team sports and contact games mimic hunting and battle skills. Anthropologists hypothesize that playing competitive games as teammates may have helped early humans develop the strategies needed to take down large predators or raid rival settlements.
Notice how many sports still involve a net or a target - soccer and basketball, where you aim to get an object into the net, or shooting, archery, and the javelin throw, which mimic hunting skills. On the other hand, equestrian sports, fencing, wrestling, boxing, and the martial arts are related to battle skills, while running, swimming, and jumping likely evolved from the need to evade predators.
The stadium is a savanna with seats.