Saying early humans weren’t conscious because they lacked complex language is like saying they couldn’t see blue because they didn’t have a word for it.
The basic assumption he attacks is that “there is a world we discover” vs “there is a world we create”.
It is hard paradigm shift, but there is certainly reality in “shared picture of the world” and convincing people of a new point of view has real implications in how the world appears in our minds for us and what we consider “reality”