Actually the reason they missed every shot when they were shooting at the main characters in the Death Star is because they were explicitly told not to hit the main characters in the Death Star, as Leia immediately points out when they escape the Death Star. Which we later see verified when the Empire follows them from the Death Star to Yavin IV with a tracking device

And don’t even bring up the ewoks. Remember that time the US lost the Vietnam war? Home turf advantage is a thing in real life.