How did Capra envisage the American Dream?

I would probably focus on Mr. Deeds Goes to Town, Mr. Smith Goes to Washington and It's a Wonderful Life. I think his outlook was formed by the effects of the Depression on America.

These movies show Capra's acceptance and support for the New Deal. Sometimes the little guy does need a little help. If unregulated big business is left to itself, then the little man will suffer.

In Mr. Deeds, Longfellow inherits money and tries to use it to help the unfortunate get back on their feet. He is particularly interested in giving them the tools so that they can then help themselves. He battles the fascist like characters who are more interested in making a profit at the expense of the "little people".

In Mr. Smith, Jefferson Smith goes to Washington to help and is again confronted by corrupt, fascist like characters who are willing to put aside the interest of the people so that they can make a profit.

In It's a Wonderful Life, George uses the savings and loan to help the little people. When the greedy banker gets a chance he crushes George and all the little people along with him.

In each of these situations it is the individual fighting against extreme odds that overcomes diversity and emerges triumphant.

Good Luck!