When they reach the sacred paintings, it seems to have been worth the painful climb. The meaning of the paintings isn’t known. The kid’s remark suggests that this mystery actually makes the paintings more valuable, not less. In other words, just because the meaning isn’t clear doesn’t mean they’re not conveying something truthful and worth hanging onto. This could be interpreted as a comment on the stories Eldon tells Frank, too, though it’s unclear if Frank realizes that yet.