Ralph is not innocent in chapter one, and he is not innocent throughout the story, even though he does try to "do right". In chapter one, Ralph is befriended first by Piggy. All Piggy asks is that Ralph not call him Piggy. However, despite politely asking Ralph not to call him this, Ralph starts out by chanting it:
"They used to call me Piggy."
Ralph shrieked with laughter. He jumped up.
Piggy clasped his hands in apprehension.
"I said I didn’t want—"
However, Ralph is not entirely ill-intentioned. He teases Piggy, but later he "attempts" to stand up for him. When Jack and the choir boys arrive, Jack screams:
"Shut up, Fatty!"
when Piggy keeps talking about rules and procedures. Ralph shouts back:
"He's not Fatty! His real name's Piggy!"
Simon and Piggy are innocent boys. It would not occur to them to bully or to tease anyone. Ralph is not innocent. However, he is not corrupt, in the way that Jack is. He has merit, and it is this that will stay with him through the end, despite the shift in power on the island.
I think that one of the main themes of the book is that man as a whole is not "innocent"--Golding shows that "civilized" boys can and do transform into destructive, ruthless creatures under the right circumstances. Ralph is, however, as innocent as most children are at the beginning of the book. He is not without guile, however, and he proves to be a good political strategist: he manages to get elected chief, but then allows Jack, his opponent, to take charge of a group of hunters. It is a gesture that keeps the peace on the island for a lot longer than would have happened otherwise.