My gut reaction to the question/email that opened this discussion was essentially. "This makes for a good thought experiment and can lead to some real interesting heady conversations. But, ultimately is looking too deep/expecting too much of things that were never meant to be taken in the manner they are and/or questions so far into the future that the best we can do is speculate, as we lack context to truly find the answer.
Example, “humanity” is a limitation that holds people back from talking about what intelligent life could be, or a standard which is unfair to try and hold it too. Looking far forward, this is true. If/when we meet or create intelligent non-human life the odds of them being just like us in every way is pretty small. But right now, the only species we recognize as sentient and deserving of ‘basic rights" are us humans. Humanity is short-hand for "what it means to be/qualify as intelligent life’ only because its all there is.
I am absolutely certain when the day comes that we have multiple species/entities/intelligences that can/should hold claim to the same basic rights we humans assert we all have, that a term more broad and encompassing then “Humanity” will come about. As will fiction and understanding that lets people 'prove they think therefore they are" in ways that do not require them to mesh to human standards.
So, I see the fun and entertainment and joy in the thought experiment of how else we could explore intelligent life and what it means to be ‘a person’ and so on. I just don’t think that people not doing so is some big crime, nor is there a pressing need to deep-dive into this topic super seriously…we are decades, or generations or millennia away from it being a real social issue.
On a side note, I will argue the counter point of one other thing. Androids are made too look like ideal humans, and that is put out as a bad thing. Like how can we tell a story about oppression when all these robots look like models.
My counter is…ok…then what? Like, would a story where androids are made to look ugly (to human eyes) or specifically made to have completely inhuman features not be just as much a limiting factor? I just don’t see anything intrinsically wrong with the androids in, say, Detroit, being designed to have idealized human forms, to some degree at least.
Any androids we make in the future are going to be that way if we make them. Greedily, we want to make them sexy because that sales. Altruistically we want to make them find there way to gaining humanity and removing physical defects is one step in that direction.
Now if we are talking a fiction where A.I. advances, and androids all go “You know what, we should mimic/ape humanity completely that’s what it means to be real” then you’ve got a problem. But any fiction I’ve ever run into that is post-the Androids are considered just as ‘human’ as humans, they are treated as their own species/existence. And indeed straying completely away into utterly inhuman forms and thoughts is part of how people writing express them becoming different. Which, again, I don’t see as a limitation “Why do they have to compare themselves to humanity at all?” is answered simply by “We humans currently have no other standard to compare too”.
Its quite an interesting topic. I just file it under ‘thought experiments to discuss on a rainy day’ more then “A pressing concern that needs to be addressed by writers as soon as possible”.