There is a physical separation between the brain and the nervous system – the brain is placed in the skull, while the nervous system are the nerves that enter the skull. The following Wikipedia article describes the connections between the brain and the nervous system.
For the purposes of what we're discussing, I think a definition based on an almost arbitrary location (almost not completely - the skull provides structural support and protection needed due to the large size of the brain, which is essentially about as strong as a jelly - in other words this little to do with the brains function beyond physical limitations that everyone has (our size and shape and all the factors that limit our physical abilities - just as there's a physical limit on how large an insect or other invertebrate can be).
What's important in my view is function, and how you can separating brain from nervous system in terms of function, that would provide an explanation for the differences between autistic and allistic (non-autistic)?
The corruption of data could happen at any stage; you have mentioned the majority of stages. Nerves could be damaged during a physical mishap such as a fall, complicated birth, and few more. There is no single cause of nerve damage.
Putting aside the (imho) important aspect of defining what you actually mean by damage, this was my argument that brain/nervous system damage invariably results in unpredictable loss of correct function.
I can appreciate and understand that you are most likely going on the evidence that's most meaningful and appropriate in your circumstance, and you may well be quite accurate in your definition of what effects members of your family and the information you've mined that relates to their condition(s), but that doesn't mean you can apply your personal experiences with a whole field of medicine, however much it may seem appropriate from your view.
One of the confounding things about autism is the huge variety of detectable physical differences of which few if any are always common to all autistics and hence inadequate as a reason for autism, and this is, I believe, why diagnosis currently has to rely on behaviour instead, but a behaviour alone isn't sufficient as it can have multiple causes, so it requires a statistical measure of those behaviours found so far that show a significance in those already diagnosed (being no other measures available). I hope you can see this in itself is a chicken/egg situation, but more to the point, just how subjective this is tending toward?
But in addition, how are you actually separating other mental health diagnoses such as schizophrenia from autism (especially as even the specialists in the field are not of a consensus as to even the diagnostics, and especially the causes. We may for example know genetics plays a definite part, but not exactly how those differing gene's come to create the symptom's we categorise as autism?
When I hear an argument based on an unexplained phenomena, I'm afraid (purely from my own view) I'm literally unable to accept it as anything more than a suggestion, and it's only by presenting actual evidence along with a rational explanation as to how that evidence confirms the theory, and most important, providing references to all sources from which vital parts of the explanation come from, so if I wish, I or anyone else can also follow that trail independently.
Anything else remains a suggestion, and the harder I find it to get specific answers to the questions I ask in order to gain an understanding of what's being proposed, the harder I find it to accept without that opportunity for independent appraisal. (This isn't me trying to say I'm more clever or whatever, I simply can't accept things without a logical framework that fits the narrative, whether I want to or not (to the best of my awareness). Doesn't reflect on the idea presented, just reflects on my need for a rational explanation to be able to accept new concepts.
Without something far more specific about what kind of damage you mean (because there are many that couldn't fit this theory - e.g. catastrophic acquired brain injury almost never results in symptoms that on their own could diagnose that damage beyond saying there's something broken in a specific functional area (speech centre, for example), because there are too many causes of those symptoms. Without significant qualification, just saying 'damage' is the cause is meaningless really, and doesn't progress the science.
But more worrying is the use of the term 'conspiracy theory' to describe how the theory could be considered (I'm
not saying
you are a conspiracy theorist!). If the argument comes from a particular source, then if that argument is to hold any scientific value then that source needs to be qualified and to state it's reasoning clearly. If you can't separate that theory and the evidence it's based on from whatever could point to it being a conspiracy theory, it would appear to have failed a test of validity, because it's relying on something that's unscientifically assumed to be correct and lacks the evidence to support itself. This means it has gaps that are not adequately explained and need to be if it's to show it isn't a conspiracy theory.
BTW, bear in mind there are plenty scientists who will, being humans, lie and cheat for personal gain (and other reasons I'm sure). I've seen some very compelling articles by qualified and experienced scientists that are utter BS, and mendacious in origin, but because they know how to write scientific papers, and are using terms few mortals would understand lacking the years of learning it can take to become expert enough to fully understand them, they can easily produce a piece of writing that subverts and perverts the original science for non-scientific purposes.
The classic "volcanoes produce more carbon pollution than humans" article won a lot of "don't know's" over to the cause of climate-change denial in part because it looked very authentic to a layman, and the vast majority reading it were laymen - the more knowledgeable knew it was BS and ignored it - despite my ignorance on the topic it still took me about two minutes to find out the guy was employed by Australian mining conglomerates ad yet again the adage of "follow the money" distilled things down to the reality of his propaganda very quickly.