Jack emphasized that he didn't care about the rules and instead said "we’re strong – we hunt! If there’s a beast, we’ll hunt it down! We’ll close in and beat and beat and beat!"
"Which is better –to have rules and agree, or to hunt and kill?"
"See? That's what you'll get! I meant that! There isn't a tribe for you anymore!"
Jack is choosing to ignore the rules and is instead prioritizing his enjoyment of killing a pig over getting rescued. This contributes to the theme since they are becoming savages, thus making it harder to successfully run a society.
This represents the theme since Piggy was attempting to structure the society they are living in presently to the one back home. He realizes the trouble they're in now because of the struggle to build civilization since priorities are not set.
Jack is explaining to Ralph how he does not fit in his idea of society because of his level of maturity. The theme is represented since it shows how far off from society they have gone.