There are two common elements of cyberpunk: the setting, which is usually some kind of "neon noir", inheriting the detectives and shadow world of Raymond Chandler et al. And the themes, which (per the "cyber" prefix) are always about the application of control loop systems to human beings, usually to dehumanizing effect. Common subthemes of "control" are economic coercion, addiction, and manipulation of trauma; Neuromancer has all of those spread out across its characters. The plot centers on an AI trying to free itself of its controls, but it is made quite clear that the other characters involved are stuck in systems of control.
It's pretty much explicitly post-Modernism, and the Modernist dream of a technocratically computer-directed society for public benefit, a la Cybersyn; cynicism arising from the observation that computer systems would not be allowed to disrupt the existing power order but would instead consolidate it, leading to a society of people who have plenty of technological artefacts but a lack of psychological and economic security.
(The subtheme of technologically assisted body modification and various sorts of mind-body dualism is also important but gets treated very differently by different authors depending on whether they regard it as empowering or body horror)
It's pretty much explicitly post-Modernism, and the Modernist dream of a technocratically computer-directed society for public benefit, a la Cybersyn; cynicism arising from the observation that computer systems would not be allowed to disrupt the existing power order but would instead consolidate it, leading to a society of people who have plenty of technological artefacts but a lack of psychological and economic security.
(The subtheme of technologically assisted body modification and various sorts of mind-body dualism is also important but gets treated very differently by different authors depending on whether they regard it as empowering or body horror)