In june 1945,the war was almost over. what else did americans have to be happy about?

 The US economy had come out of the Depression and was growing rapidly.

The Great Depression had begun with the stock market crash in 1929 and persisted until the late 1930s.  Efforts like the New Deal had sought to address and correct problems that led to the economic depression.  However, ramping up as a supplier to the Allies and then as a participant in the Allied effort in World War II had an even greater impact on the American economy.

As reported by the Economic History Association (EHA):

The American economy expanded at an unprecedented (and unduplicated) rate between 1941 and 1945. The gross national product of the U.S., as measured in constant dollars, grew from $88.6 billion in 1939 — while the country was still suffering from the depression — to $135 billion in 1944. War-related production skyrocketed from just two percent of GNP to 40 percent in 1943.

Employment in the United States had also recovered greatly during wartime.  The EHA also reports that "in 1944, unemployment dipped to 1.2 percent of the civilian labor force, a record low in American economic history and as near to 'full employment' as is likely possible."

The US economy continued its rapid expansion in the postwar years after 1945, which became a booming time of growth and prosperity in the US.

Because the discoveries were some of the oldest human remains.

The answer is false