As I ( Charlie) remember the old school days before Title IX: the only event in which young women Baby Boomers got to display their athletic skills. Cheerleaders were usually very cute and athletic. Cheerleader outfits include sweaters, short short skirts, and cheerleading shoes. During the Baby Boomer days, the young women in their Keds cheered on the young men playing basketball in their Chucks. Others have said that the two most important attributes for a cheerleader are an attitude and a nose job.
On the Internet, cheerleaders are frequently the centerpiece of risqué stories involving making whoopee with football or basketball players. Internet cheerleaders are always getting caught in various acts of moral turpitude, for which Mother displays where her child got their athletic ability by hosting a follow-up athletic event, like a slippering.
During an athletic event, they have exactly the same function as they did in the Baby Boomer days. Except, now, some schools also have young men as cheerleaders.