Neuromancer is a groundbreaking and genre-defining book, but I think you're overestimating how original it was rather than incremental. Similar ideas predate it, e.g. Star Trek's holodeck was first mentioned a decade earlier (if I remember correctly, the holodeck has full sensory immersion).
Most human innovation is incremental. As a whole package, the book feels fresh. But examine any particular element, and you can find precursors.
You also have the benefit of choosing a classic book out of millions of published books and comparing it against a single ChatGPT response. Most books are not as original as Neuromancer, and our sample of 1 ChatGPT response probably doesn't show the full range of its potential originality.
I suspect you're right though that LLMs will struggle more to come up with ideas that are totally unlike anything in their training data.
For fun, I asked ChatGPT to come up with some original ideas for a novel:
> The Galactic Seed Vault: The Milky Way is discovered to be a 'seed vault' created by ancient aliens, containing genetic material from extinct alien species. Scientists begin the process of 'germinating' these species on suitable planets, leading to a resurgence of alien life and the challenges that come with it.
> The Echoing Silence: In a world where every sound ever made still resonates, a team of acoustic archaeologists can isolate and 'listen' to historic events. They inadvertently unleash sounds that should have remained silent, causing chaos in their present day.
> The Taste of Emotions: A society where food is imbued with emotions. Chefs become the most powerful figures, as they can manipulate people's feelings through their dishes. The protagonist, a chef, starts a revolution by serving dishes of dissent and rebellion.
> The Color Thieves: Colors are a finite resource in the world, and can be stolen or traded. A black and white underground movement rises, challenging the color-owning elite and demanding a redistribution of hues.
These were all brief and vague on specifics, so I asked it to generate a longer synopsis for a sci-fi story:
In the wake of an unparalleled climate calamity, the remnants of humanity eke out an existence in their final sanctuary: the newly-thawed Antarctica. Society has been reimagined, birthing groundbreaking systems - the Carbon Economy and the VR Democracy. These innovations, while revolutionary, bear their own set of complexities.
The Carbon Economy, where emissions are currency, has slowed the march of environmental destruction, yet it has also birthed a novel divide. The affluent, equipped with advanced carbon capture technologies, enjoy an existence in verdant metropolises, while the less fortunate languish in dense urban sprawls burdened with a high carbon cost.
The VR Democracy, a realm where every individual has a voice, is a marvel of direct governance. Yet, it's not without its flaws. The din of majority rule often silences the whispers of the minority, and the digital nature of this reality fosters a disconnection between virtual decisions and their tangible consequences.
Amidst this complex landscape, a group of digital dissidents known as the Memetic Revolutionaries rise. They wield the power of memes, not merely as vessels of humor, but as profound tools of persuasion. They craft Empathy Memes, potent capsules of shared feeling that open the eyes of the masses to the struggles of those bearing the brunt of the Carbon Economy. This emotional awakening fuels a wave of empathy within the VR Democracy, igniting a clamor for transformative change.
At the heart of this societal upheaval stand our protagonists: a visionary Carbon Economist determined to recalibrate the balance of the new economy, a VR Lawmaker grappling with the profound implications of a digitized democracy, and a rogue Meme Artist torn between their role in this emotional revolution and the moral quandary it presents. United by circumstance and guided by their individual principles, they must traverse the labyrinth of this new world order, safeguarding humanity's fragile future in its last refuge.