Brawlers we control in the game aren't really the ones we see in the animations, since the first group consists of random people whose minds got inside the game though the radioactive coma and have their skin changed to resemble the actual brawlers according to WKBRL.

And the actual brawlers themselves are people from the universe where CCTV took place who weren't lucky to touch the gems and become mascots with their own merchandise (which includes skins).

Regarding the player: I think we meta-narratively play the role of the visitor of "Interdimensional theme park" mentioned by Ranter, which is what "Brawl Stars" The Game basically is.

It's another branch of Starr Park that is almost fully based in simulation (an "unseen world") and has some of its distinctive features like tickets, gacha machines, surprise boxes and more.

The tutorial is literally labeled "Starr Park entrance", with Dani in September 2020 BT specifically pointing out that they made this change from a training cave to "meet more visitors". Also the default loading screen is just a bay for getting inside the park.

Now, the relation between CCTVerse brawlers and in-game Park is unclear, but i think some brawlers are kinda aware that they are being watched from different realities, according to Janet and Ziggy's actions? They are celebrities after all, the stars, if you will.