During the Cold War, the average American looked at the Soviets as rivals and enemies. Was this the common perception during WWII? If not, when and how did this attitude start?
Rather than try and explain the rather conflicted US views on Russia during the war, it might be useful to look at US government funded propaganda efforts that tried to promote a positive view of Russia among Americans.
A famous one is 'Why we fight'
https://www.youtube.com/watch?v=b_SZOX8ig4U
directed by Frank Capra the man that directed it's a wonderful life. It got an academy award and in later years it would come back to haunt a lot of people associated with it.