Did Ralph and piggy feel responsible for the murder?

On one hand, it's used as a reference to Christ in The Bible. Just like everyone had a hand in Christ's death, everyone had a hand in Simon's murder.

Alternatively, it can be used to reference how they're all becoming more and more savage. Ralph and Piggy are arguably the two least violent characters in the novel, and so their hand in murdering a comrade shows that, even without their intention, their separation from society aside form those on the island is making them savage and driving them somewhat closer to madness.

It's significant because it supports the civilized-to-savage theme in the book.