Actually they have shared some things together and have some strength in their relationships as a result. They have done or shared nothing with you. Get in there and share some experiences together. Soon you will be a well-accepted part of the group. Become a doer.
Every group needs help in activities.
Participate, help out to make things go and the group succeed. You will have all sorts of reasons to have contact with others and soon you will be a well-accepted member of the group. Anything where you are actively doing something or overcoming a resistance together, or sharing a unique and active fun trip or experience together helps build a bond of friendship and builds strength in a friendship.