What was the role of the littluns at the assembly?

Answer 1

While the bigguns represent government, and Jack and Ralph leading figures, the littluns are common people with no voice. They could only give their 'simple obedience' to the bigguns.

On the other hand, littluns also represents subcultures in the larger community culture, such as natives in america, whose voices are not heard.

They may also represent purity in comparison to the bigguns, like children in the community, who are ignorant of the world. in this mini-world, the bigguns symbolize adults and littluns children. The point is: Bigguns still have adults to look up to, but who do adults have to look up to?

Another answer

The littluns had no specific 'role' at the assemblies, to quote from the book... 'they obeyed the summons of the conch, partly because Ralph blew it, and he was big enough to be a link with the adult world of authority; and partly because they enjoyed the entertainment of the assemblies.'