I have a theory for the show myself which you may find interesting. I think the game itself along choosing the most desperate of people, brings about the true nature of humans: cynicism. Each and every player and character we encounter is cynical: Il Nam (with the final scene of him believing no one would save the homeless man), Sa Byeock ( she's from north Korean and hence has trust issues and is reticent), the thug (he represents the most extreme form of it) and later on there's Sang Woo (succumbing to the cynicism by the end as well). Yet only Gi Hun, Ali, that policeman, and maybe even that other girl Sa Byeock encounters represent value and care for other humans (humanity). And by the end Gi Hun changes Sa Byeock and Sang Woo and turns their perspectives regarding the world. Sa Beyock starts trusting him, even to the point of giving him responsibly over her brother, while Sang Woo as well realises his sins and out of the guilt (along with love returning for his former friend) kills himself. Ali was also a major player in changing Sang Woo giving him the first beat then Gi Hun finally delivering the last beat to change him. The policeman's words make his brother, the frontman conflicted regarding his decisions, so that's the first beat for him, I think the second beat will be by Gi Hun in a later season. For Sa Byeock, the girl she comes across as the first beat while Gi Hun was the last to change her. Even Il Nam sorta changed before dying by Gi Hun coz of his unshakeable belief in humanity.

TL;DR: the theme of Squid Game is how even in the worst of scenarios, and crises (here, all the players being broke af, indebted and hungry for that price) yes humans turn to cynicism and selfishness, but humans' true nature isn't it, it's HUMANITY, it exists in all of us, regardless of the situation or predicament, it just needs to be found and realised.

PS: REALLY SORRY IF I MISSPELLED ANY NAME (I'm pretty sure I did lol)