I agree, clearly we had common ancestors with other higher animals that had emotional lives, were creative, played games, had social lives, even mourned their dead. We do have higher brain functions than other animals, there’s no doubt, but clearly having those higher brain functions isn't necessary for having the faculties I described above. I see no reason to assume it fundamentally changes the nature of those faculties and experiences. It may change our ability to reflect on them and express them, but is likely to be independent of their fundamental nature and experience.
Actually I think this something that goes far beyond relatedness and the capacities of our common ancesters... consciousness appears to be an emergent property that is substantially similar even when it emerges in physically radically different beings with completely different neural structures.
The biggest piece of evidence we have for this is from octopi... they are about as alien as anything we can image (radial symmetry, distributed brain, visual input and output spread over the entire skin) and the last ancester we have in common with them was some kind of worm with just handful of neurons. Yet they seem to problem solve and explore and manipulate their environment much as we do, and people have developed surprisingly close relationships with some octopi in captivity. Even with an octopus, when you get to know it you begin to feel the kinship that seems to always be possible between one conscious being and another.
