> Are there people who are not on said spectrum?
Yes.
Autism spectrum disorder (ASD for short) is a neurodevelopment disorder. I'm quoting verbatim from Wikipedia:
"characterized by symptoms of deficient reciprocal social communication and the presence of restricted, repetitive, and inflexible patterns of behavior. Autism generally affects a person's ability to understand and connect with others, as well as their adaptability to everyday situations, with its severity and support needs varying widely across the spectrum."
Within this spectrum you have "high functioning" individuals who are capable of living self-sufficient, productive lives on their own (individuals with what we used to describe as having asperger's syndrom) and on the other end of it you have individuals who will always need constant supervision because they can't communicate effectively enough to hold a job, nor can they be trusted around kitchen appliances.
Common characteristics of ASD are:
- Regular difficulties in social interaction or communication (note the word "regular", everyone struggles from time to time. Someone with ASD experiences this permanently)
- Restricted or repetitive behaviours (examples: not using hand gestures when speaking, rocking motions etc.)
- Resistance to disruptions in routine (many people don't like routine disruptions, someone with ASD usually finds this to be crippling)
- Restricted interests (getting obsessive about hobbies but also really not giving a shit about things that most other people care about, like small talk or even major life events in the lives of loved ones ... like I couldn't give the slightest crap that my sisters got married or that I'm an uncle, and I like my sisters and their kids)
- Not enjoying human touch. I don't like being hugged or kissed, even by my wife or children. Even as a 42 year old adult, I hold my breath when I'm in the company of strangers because I find the idea of inhaling the air that they just exhaled to be gross.
There are more. But someone who is "on the spectrum" will exhibit many of these characteristics and exhibit them permanently throughout their lives. Whereas for "neurotypical" people, these may be fleeting or they may experience one or two in isolation... whereas ASD is a prolongued pattern of many of these characteristics together.