The American people are, of course, not one monolithic mass. Different groups of people were impacted in different ways. As a whole, the American people were helped by the war because it catapulted the US into its post-war status as the world’s leading economy. Outside of that, different people were affected differently.
One group that was affected by the war was women. During the war, women often took the places of men who had gone away to fight. They filled roles that had previously been closed to women. After the war, the men came and took their places back, but many women’s attitudes had been changed by the experience. It was the generation of Betty Friedan (born in 1921), for example, that helped to push feminist thinking to the fore.
Another group affected was African Americans. They participated in the war like everyone else, but were put in segregated units and, in many cases, relegated to menial labor. Having fought for their country made more of them feel that they should push for equal rights. The rhetoric of the war against Nazi racism also gave them more of a feeling that they could win more rights. Less than ten years after the war, the decision Brown v. Board of Education had been handed down.
Finally, there were the impacts on rural and working class men. The GI Bill made it possible for many more of these men to attend college. This allowed them to find their way into white collar jobs and into the middle or upper-middle class.
In these ways, WWII affected different Americans in different ways.