In the books, the role of the Atreides family was not to be the good guy but the necessary evil to reach the final step of saving humanity. Even Paul can’t stand his own role in the story.

It’s complicated. Paul isn’t really a good guy, but he’s not really a bad guy either. He’s just a dude. He’s a dude who has limited vision into the future from which he cannot escape. He’s not using his future vision to pick the bad choices he’s trying to pick the best ones he can and the hand he’s dealt kinda just sucks.

Not so much opportunistic but unavoidable. He’s a slave to the powers surrounding him, and the more real-world power he attains the less choice he has in how to wield it.

The real gut-punchers of how his station is betraying Paul’s actually and genuinely good character are going to come in the second book, that is, subsequent movies.

And, yes, Paul, the Atreides in general, are good people. Noble, honourable, just, wise, kind, upright, everything, to a fault. Which is the only way to tear down the Messiah archetype, the Messiah has to fail despite their virtues, the failure has to be dictated on them by the universe, in a way that’s not incidental but an unescapable truth about how the universe works. Or at least humanity.

I’d say Paul’s rise is portrayed as a mixed event throughout the books that depends on the perspective of different factions and what time period you view it from, but overall the main characters see it as good as the end of the first book. The movie doesn’t try to explain many of the details that didn’t fit into it’s cinematic storytelling style (you get almost none of Paul’s thoughts and struggles) so there is a lot of clarity that can be provided by the book. I think the movie left less of a sense of his ascension being motivated by good intentions (and magical foresight/inescapable destiny) than the book did, so it’s a less optimistic ending.

The Fremen saw it as a good/liberating event and Paul as a true member of their tribe, and he genuinely seems to internalize that into his sense of self. (From the reader’s perspective, this is disregarding the white savior bias of the book that the comment before yours alluded to. Paul is a colonizer who is sympathetic to the natives and helps them lift themselves up in ways the book implies couldn’t have been done without his help). Overthrowing the Harkonnens and the Emperor’s forces leaves the Fremen and moreso Paul in an overwhelmingly powerful position as Arrakis is the only planet able to produce spice at the time.

This is juxtaposed with the view of the nobles, the spacer’s guild, and the populations of other planets that is explored in later books. Fast space travel is only possible due to the effects of spice that allow the navigators of the space guild to see short distances into the future to avoid collisions, etc in space travel. Control of the key to space travel grants the Fremen immense political and economic power, but also puts them at odds with the rest of the empire who are reliant upon the spice.

One aspect the movie didn’t explain well is that the Fremen were not motivated by gaining the political and economic power of spice, but instead envisioned an Arrakis that was no longer a wasteland. They developed plans to terraform the planet to make it more hospitable and liberation allowed them that opportunity. On the flip side, spice is produced by the worms, but water is toxic to the worms (the scene with the worm dying in water isn’t just from it drowning), so if they are able to accomplish this goal, spice production will be eradicated, affecting space travel everywhere.

I don’t want to spoil the story after the first book because I believe they will explore it further in the movies. Ultimately, the first book is a story of liberation as well as a coming-of-age story for Paul and the outcome is generally seen as positive by the majority of the characters you get the perspective of. The ones who are opposed are portrayed as grotesque embodiments of evil, like the baron Harkonnen (the movie was too nice to him and cut out the pedophilia, though it kept some of his sadistic and cruel tendencies).

Whether your views of the events of the first book will hold up over time might depend on the events that happen next in the series. There is fallout from everything that happens in Dune as it’s very much a story focused on political machinations. Something that is good or bad may turn out to have consequences with the opposite effect down the line.

Lots of contextual details were left out of the movie as well as a lot of the character building, so I suggest reading it if you are interested. The first 100 pages are tough to get through, but then it goes smoothly. For example, the lack of detail in the movie makes Chani and Stilgar feel fragile and insecure rather than resolute and pillars of strength/growth for Paul, Jessica sees less focus and you get little exposure to her thoughts, there is a miniscule amount of light shed on Paul’s thoughts throughout the movie, so he comes off as callous in the movie while he is far more empathetic in the book.

I only read the books so the movie may have course corrected somewhat to make that clearer. I feel like in the books it was a little bit like greek tragedy but Paul gets the “shades of grey” treatment for much longer than he deserves.

I have to admit a bias though that since the books kind of go off the rails pretty quickly I tend to prefer to look at Dune as a stand alone work strictly from an enjoyment standpoint.