I think it's about how there are kind of epochs of humanity, like the difference between most animals and humans seems massive right, so then look forward and try to imagine what that next epoch would be like where our current state is an animal compared to the next? So the reflection in the first section looks at humans when we were similar to animals and then a key innovation that helped us progress, tools.

then we jump ahead and while it's the future it's clear that we're looking at the same humans as ourselves. We see Hal and Hal is kind of an alternative, just as if another set of animals had won in the reflection section.

Then we jump to the next thing, the next big progression.