Actually, Jesus was NOT showing the importance of community; he was showing the importance of faith. Several times in the gospel, upon healing a person, he comments, "your faith has made you whole." He was not in the business of healing those who did not believe that he had the power to do so--he was not in the "prove it" business.
As for forgiving the man's sins, it was a common belief among the Jewish people that sickness, lameness, etc. were God's punishment for sin. On this and on several other occasions, Jesus indicated that this connection did not exist. He rather used those who were ill to demonstrate the light of God's love:
As he went along, he saw a man blind from birth. His disciples asked him, “Rabbi, who sinned, this man or his parents, that he was born blind?” “Neither this man nor his parents sinned,” said Jesus, “but this happened so that the works of God might be displayed in him. As long as it is day, we must do the works of him who sent me. Night is coming, when no one can work. While I am in the world, I am the light of the world.
Jesus himself indicated many times that he came not only to preach the gospel, but also to heal the sick:
And the scroll of the prophet Isaiah was handed to him. Unrolling it, he found the place where it is written:
“The Spirit of the Lord is on me,
because he has anointed me
to proclaim good news to the poor.
He has sent me to proclaim freedom for the prisoners
and recovery of sight for the blind,
to set the oppressed free,
to proclaim the year of the Lord’s favor.”
Then he rolled up the scroll, gave it back to the attendant and sat down. The eyes of everyone in the synagogue were fastened on him. He began by saying to them, “Today this scripture is fulfilled in your hearing.”
By healing this man who was lame, he was fulfilling his mission on earth. At the same time, he indicated the importance of faith.
This is a great question. It is always good to apply the theology of a passage to real life.
In chapter 2, Jesus does heal a paralyzed man, but there are two other interesting points. First, the paralyzed man's friends bring him to Jesus. This makes sense, because a person who is paralyzed cannot walk. Second, Jesus not only healed this man, but also forgave him of his sins. In light of this, we can make several important points about how this passage relates to people's lives.
First, according to Jesus, community is important. Jesus heals the paralyzed man in view of the faith of his friends. Mark suggests this, because the text says that Jesus saw the faith of his friends. In light of this point, Jesus is showing us the importance of community.
Second, the gospel writers are intentionally trying to show that Jesus is the messiah. In other words, he is the one who fulfills the Old Testament. If you recall, there are places in the Old Testament, which speak of the lame walking in the advent of the messiah.
Third, the fact that Jesus heal and forgives this person also show that there is a spiritual point. Jesus is the one who forgives the sins of people. This is important, because one of the great maxims in our world is that no one is perfect.