Actually this isn't the case. The point is that the documentarian tries his best to NOT negate the octopus' actual life, and to be as neutral and as trustworthy as possibly to the octopus so that he can observe and document what the life of an octopus is actually like, and through this, the octopus actually learns to see him as a curious being that it wants to interact with. And through learning to appreciate the ocean environment without dominating it, and through the generosity of the octopus deciding to interact with him, he learns more about himself.

It's not like he went into the project thinking "I want to find myself and have all these lessons by befriending an octopus". He wanted to document the life of an octopus and in the process happened to grow as a person and thus told the story of both things.

Now he has created an organisation of people who protect the ocean with him, so it's a very environmental film not a "humans dominating animals" film. And most of the coolest stuff about the film was that it documents a lot about octopuses that naturalists didn't know before, like their ability to pick up rocks to cover themselves like an armoured ball that is protected from predators.