At first, the description of Ralph would certainly seem to suggest that he is a good person. In the first chapter, Golding writes that Ralph "might make a boxer, as far as width and heaviness of shoulders went, but there was a mildness about his mouth and eyes that proclaimed no devil."
So the reader can safely assume that Ralph is not interested in doing anything bad. And the rest of the physical description of Ralph is such that he clearly has some natural charisma and the boys are drawn to him, enough to vote for him despite the fact that Golding writes that "the most obvious leader was Jack."
Golding goes on to describe Ralph and note that "there was a stillness about Ralph as he sat that marked him out: there was his size, and attractive appearance; and most obscurely, yet most powerfully, there was the conch." Ralph has this natural authority that is magnified by the conch. And he begins his reign as chief exhibiting a natural concern for the other boys and trying to organize things in order to be rescued.
And at the end of the story, Golding writes that Ralph "wept for the end of innocence, the darkness of man’s heart, and the fall through the air of the true, wise friend called Piggy." Golding gives Ralph a clear understanding of what has happened and Ralph is clearly heartbroken over it, again suggesting a good moral character. Ralph wishes that the boys had not descended into such savagery (himself included).