This is almost a "trick" question because the whole point of the story is that the addition of Tommy Luck to Roaring Camp CREATED the positive society of the camp itself. Therefore, at best, it is very difficult to answer the question because I believe the statement above to be true and that the importance of the characters is, specifically, in the camp as a UNIT. However, because you have asked, I would say that in my opinion the characters in the story (the men of Roaring Camp) represent the fringes of society and, with the addition of Tommy Luck, become better integrated with society as a whole.
At the beginning of the story, the men of Roaring Camp represent the fringes of society. They are forty-niners, rough and dirty. They house the prostitute Cherokee Sal (perhaps for her "services"). They curse better than sailors. They pride themselves on looking for the materialistic gold nuggets that called them there to the far west.
It is the entrance of "the Luck" into their camp that causes the men of Roaring Camp to begin to change and, by the end of the story, to change into men possibly able to fit into society. For example, only the VERY beginning of change can be seen with Kentuck's reaction to the baby grabbing his finger.
He rastled with my finger, ... the damned little cuss!
Kentuck becomes overwhelmed with emotion after that line and begins to cuss a lot less! It is a bit later, at what eNotes calls a "rowdy Christening," that the baby is given the name Thomas Luck (affectionately called Tommy Luck or even "the Luck").
Gentlemen will please pass in at the front door, round the table, and out at the back door. Them as wishes to contribute anything toward the orphan will find a hat handy.
The child is given the name of "the Luck" and almost immediately becomes a self-fulfilling prophecy and the reason for the title of the story. Suddenly ALL the men seem to become prominent citizens!
They’ve got vines and flowers round their houses, and they wash themselves twice a day. But they’re mighty rough on strangers, and they worship an Ingin baby.
To state the opposite of what was mentioned above (from the beginning of the story), they are gentle and clean. They have not hired another prostitute. They have cleaned up their language. They have all but ceased to look for gold and are FAR more concerned with the caregiving of Tommy Luck. They have become, as a unit of men from Roaring Camp, a proud father.
In other words, the way the men of Roaring Camp are at the BEGINNING of the story (examples of the fringes of society) is different from the way the men of Roaring Camp are at the END of the story (easily integrated into society as a whole).