What do Samneric symbolize?
It's fascinating sometimes to look at the journey of a minor character or pair of characters through the novel. I'm not sure Samneric are representative of any particular type of person in society, though Golding does use them to delineate the growing power of Jack.
Initially, they stick with Ralph, despite Jack's glamorous attraction: here's Ralph talking to Piggy
"Piggy? Are you the only one left?”
"There’s some littluns.”
"They don’t count. No biguns?”
"Oh—Samneric. They’re collecting wood.”
You see Samneric come to want to be part of Jack's tribe, for example, when Ralph forbids them from painting their faces:
“Well, we won’t be painted,” said Ralph, “because we aren’t savages.”
Samneric looked at each other.
“All the same—”
And, in that pivotal scene of Piggy's death, it's Samneric, the good people who resist the temptation to join up with Jack's savages, who are used as hostages and bait. Jack knows that symbolically they are the support Ralph needs to be chief.
No one moved. Jack shouted angrily.
“I said ‘grab them’!”
The painted group moved round Samneric nervously and unhandily.
Once more the silvery laughter scattered.
And finally, they crack:
“What d’you mean by it, eh?” said the chief fiercely. “What d’you mean by coming with spears? What d’you mean by not joining my tribe?”
The prodding became rhythmic.
The final chapters of the novel show Samneric as signed up members of Jack's tribe. They're the good guys corrupted. Golding's point? It happens.