Why does the boy want to join the older boys?

To me, this is a way for Jerry to show that he is
independent.

If you look at what his life must be like, you
can see why he would want to go to join the boys.  He seems to be the only child of a
single mother.  His mother seems to be a bit overprotective of him.  I think that young
kids always want to be more independent and a boy in this situation would want to even
more than normal.

So I think that he wants to go join the
older boys to show that he is independent and that he is able to be accepted by people
who are more of his peers.