"Courage & sacrifice in the face of adversity" is basically synonymous with the term "hope", and you've just kind of insinuated that there was no hope present in a movie that's literally called "A New Hope", within a franchise with probably the most famous underdogs in all of cinema (the Rebels). So when you say "courage and sacrifice are largely absent from the franchise", it makes no sense - it's like saying "The themes of war and death are mostly absent from Saving Private Ryan". It's just... wrong.
Well, no, they are not synonyms. A person can have hope that something will happen without being able or willing to take any personal risk to make it so.
In A New Hope there is never really any sense that the protagonists are at risk, and where there there are consequences they tend to be glossed over or minimized. So Luke's Aunt and Uncle are killed, but (a) we barely knew them, (b) it occurs off-screen, and (c) Luke mourns them for about 5 minutes and then the movie pretty much forgets about them. Their deaths are really a plot device to
free Luke to go Jedi-knighting. Alderaan is destroyed, but we never met anyone from there except Leia, we are given no sense of their culture or what was lost, and like the trope says,
a million deaths is just a statistic. Kenobi doesn't really die, he clearly allows himself to be hit (if he even was, he may have ascended prior to being struck), his body disappears and he ascends to Force Ghost status. Luke mourns Kenobi's death more than he does his Aunt and Uncle, but between Obi Wan's warning to Vader about becoming "more powerful than you could ever imagine" and the disappearance of the body, the audience is pretty sure that something else is going on. None of these deaths generate much in the way of pathos,
nor are they meant to, because the movie is not about sacrifice or loss or the human condition, it is about faith and mysticism and rebirth/the afterlife, since you literaly have Kenobi ascending to another plane and coming back to tell Luke to trust in the Force.
BTW, none of the characters in A New Hope actually have their hope renewed. Luke was fine before the movie starts, Han was content with his lot, and the portrayal of Leia never suggests she lost hope. The "New Hope" might be the renewed hope of the rebels because of the destruction of the Death Star, except we hardly get to know them before that happens. I think the "New Hope" is Luke, the Chosen One, the one who could balance to the force (but didn't, as far as I can tell, but then I never saw ep. 8-9). Or at least I think he was supposed to be the Chosen One in 1981 when the "New Hope" title was released, before the Chosen One was retconned to be Anakin.