There are a bunch of guys and they fall. I think there were also gals, but maybe they were guys in drag since the game it's called "Fall Guys" and not "Fall People", unless it's like an X-Men case where they have female, gender-fluid or non-binary members despite the team's male name.
Why do the Fall? They're competing in a tournament to get crowns. Why do they compete though? Are they forced against their will to compete? is it a long going tradition? or are they adrenaline junkies who can't live without the thrill of falling at high speeds?
So many questions left up to interpretation of the players. It might seem like a cutesy title, but this game is far more deep than your average battle royale.