The growth in Silas Marner is illustrated in many different ways. There is an overall growth maturity, because people moved out of their comfort zones and opted to accept Silas Marner as part of their community. This alone is a huge step in the process of human growth. Second, there was an overall growth in how their manners went from provincial and reductionist to open and caring: The people of Raveloe collectively felt pity and compassion for Silas, the man they once thought was enigmatic and insolent.
There was also a growth in community relationships: As the boundaries of isolation and myth came down, the community realized how neccessary it is to support those in need; what happened to Silas could have happened to any of them. How would have they wanted the people to react towards them?
Last, but not least, there is the growth in Silas's character itself. Silas changed. He began as a wounded man with a grudge against the world, as an isolated man who wanted nobody near him, and as a greedy man who wanted to share nothing. Yet, this horrible event in his life (his second big fall) taught him a better lesson than the first one: It taught him to be humble, to shift his purpose in life, and to accept that life is unpredictable, unfair, and that one's job is simple: To keep on living.
Therefore, the growth we see in Silas Marner is proportional to the fact that one event moved an entire community towards unity and understanding, and that this event also helped change their lives and growth, as a community, together.