BY ROBIN SIDEL

Surprisingly confident consumers and small-business owners helped propel J.P. Morgan Chase & Co. to a 55% profit surge in the first quarter, increasing optimism among investors that U.S. banks are rebounding from the crisis that staggered the industry.

For the first time since the housing bubble burst, J.P. Morgan Chairman and Chief Executive James Dimon expressed hope that the worst is over, citing broad economic improvement around the world and signs of recovery in loan categories ranging from credit cards to mortgages to small businesses.

“This could be the makings of a good recovery,” said Mr. Dimon, who warned that …