I am an autist in a family filled with autists - some of whom I think you would CLEARLY recognize as autistic, but some of whom you'd have this "absolute nonsense" reaction to. I say that because that is the reaction I had myself, I was very skeptical of this whole thing until I came to learn a lot about it after my daughter was diagnosed.

I don't think it's mainstream science, but monotropism is a theory of attention which has been theorized as the central underlying feature of autism and you might be interested in looking it up. It makes a lot of sense to me. I think the more mainstream way of talking about it is bottom up processing (details, the trees rather than the forest) vs top down processing (holistic, the forest rather than the trees).

Either way - you can get a very diverse set of results depending on how which sorts of things the individual's attention gets commandeered by, and by how much. Some people can't stop paying attention to individual sounds or individual tactile sensations or any other individual sensation, some people have difficulty putting sentences together despite having an excellent grasp of each word, some get stuck trying to process specific individual facial expressions and fail to grasp the actual social dynamics going on around them - it goes on and on.

Some have special interests (deep attention to a specific topic) that are extremely economically profitable (programming) or simply socially mainstream (music or movies) which give them social cachet. Some have special interests that mark them as weird and socially outcast (collecting bugs, memorizing bus routes). Some are very intelligent and are able to make up for a lot of difficulties with effort. Some have a great focus on social dynamics and come off quite charming. All of this can add up to very different experiences though life, very different sets of difficulties, and that of course can compound.

I think you should expect there to be a very wide variety of autistic people, if there is an underlying similarity in processing things. There is a very wide variety of non-autistic people, too. Heck, I think there's a wide variety of people with only one hand, just because Jim Abbott was a major league baseball pitcher doesn't mean he actually had two hands, and just because Muggsy Bogues was a great NBA player doesn't mean he wasn't short.