While Dragon Ball Z has always been a series that included prominent cyborg and android characters (17, 18, Cell, and even Frieza), no one ever thought Goku would be on that list. Goku is famously a Saiyan, an alien from Planet Vegeta, but originally, Goku was going to be a cyborg. At least, based on Goku’s ‘prototype character’ from a series Akira Toriyama created before Dragon Ball – one that looks like a nearly shot-for-shot storyboard of what Dragon Ball would become.
https://screenrant.com/goku-originally-cyborg-not-saiyan-dragon-ball-z/