Dune has the sub-theme of tough conditions create tough people. The sand people were just waiting for the right spark.
I mean yes, but that’s a bit of a surface level read and I would argue more of a trope than a theme. Like there’s a lot of fantasy where there is a scarcity based culture that makes for skilled people with very survival forward approaches to things normally governed by sentimental attachments that paint kindness as a privilege of those with resources to spare…
Those conditions in fictional tropes pre 1960’s were just more often than not just temporary generational stuff. Famine, war, extreme poverty and so on were popular places to draw touch characters from but the sci-fi boom just elaborated it into death worlds where things are always horrible as a matter of a more overarching environmental nature. People have otherwise been on their box about the effects of soft living on moral character since as long as the written word has existed.
If by surface level read you mean reading what the author wrote, then I agree. I think in this case, what the reader brings to the story is most important. I have training as a biologist so, survival of the fittest is right in my arena.
It is what the author wrote but it’s basically like saying Winnie the Pooh has themes of childhood innocence… Yes. It does, sure, but would you bother writing an essay on it? Deeper reads of the text give you a lot more subtext. Like for instance how the plight of the Fremen and the spice trades mirror the political situations in the Midde East, Atraidies and Harkonnen are rips of Greek and Finnish names with many of the main offworld characters having Biblical (Hebrew or Roman) names while Fremen are specifically sort of coded as Bedouin /Islamic Zen Buddhist mashups and sometimes they straight up speak Arabic. So the offworld Empire gets kind of “Western Civilization” coded and the desire for emancipation is taken over by an inevitable religious fanatism caused by essentially an offworld sympathizer who is the result of hundreds of years of Eugenics becoming a messiah figure basically being a better indigenous people then the indigenous people who are ultimately pawns in a female lead conspiracy that fucked up because of one woman’s choice to have actual reproductive autonomy…
Dune’s got a lot subtextually going on worth talking about but “Tough conditions tough people” isn’t what I find interesting about the story. I get that from a lot of places so it doesn’t feel particularly unique or special to the story.