No, the fact that people have grown up to very limited or even arguably nonexistent consciousness, but still perfectly functional, capable and alive, means that. Functional enough to survive 7+ years by himself in a French forest. Add that these cases prove that perfectly healthy and normal human minds might never achieve consciousness, or at least nothing exceeding whatever consciousness a cat or dog achieves. There was no medical problem preventing consciousness, we don't even really know what the problem was, or perhaps I should say which of the many, many problems this child faced caused this. Lack of human contact ? Upbringing by wolves (assuming that actually happened) ? Was it surviving by himself ? Was it the water ? Perhaps a forest is just a uniquely bad environment for kids ? Perhaps even that specific forest ? Perhaps there was a human or animal or even something else in that forest that somehow further traumatized this kid ?
You'd have to give definitions of consciousness that don't include human contact, don't include language, symbols, any human other than yourself at all, or any thoughts at all not related to short-term survival, don't involve realizing you (as a human) are obviously not a wolf, ...
It also means that there is a period where you can be taught consciousness, and clearly if it doesn't happen before 7 years of age, you will never learn it.
I agree with most of your points, but I see no reason to assume that someone who cannot use language is not conscious. After all, use of language is just one of the brain’s functions. It’s not an emergent result of logical reasoning or something like that. On the contrary, it’s a task the brain evolved to perform, and has “hardware acceleration” for – that is, regions of its genetically encoded floor plan which are dedicated to it. If that accelerator is disabled due to not having been initialized properly… that’s no reason to conclude that the rest of the system is also defective.
It does seem clear that language assists consciousness in most people – e.g. most people report experiencing an internal narrative. But some people don’t. And even if everyone did, I don’t think that would be strong enough evidence to conclude that language is required for consciousness.
Given that most definitions of consciousness I've seen essentially express that you are capable of symbolic/abstract thinking, I'd say:
1) (extreme) autistic person that doesn't speak, but can, and arguably thinks too abstract, rather than not enough : yes, conscious. Probably more conscious in some sense than "normal" people, whose consciousness is more a group thing, or at least less independent.
(also: not speaking is a pretty extreme form of autism, certainly not something you'd see in your average school)
2) person that grew up without ever having any reason to learn symbolic or abstract thinking ? No, not conscious
But it's going to be a sliding scale thing. By some measures a cat and a dog are conscious because, well, because they are certainly capable of making humans think they are suffering (and therefore they both think and feel, which is where consciousness definitions are going on now. Fish, for instance, are not). This seems to me a really bad way to define it but it's certainly widely used.
You'd have to give definitions of consciousness that don't include human contact, don't include language, symbols, any human other than yourself at all, or any thoughts at all not related to short-term survival, don't involve realizing you (as a human) are obviously not a wolf, ...
It also means that there is a period where you can be taught consciousness, and clearly if it doesn't happen before 7 years of age, you will never learn it.