Having bridged both worlds, here's how they are viewed as described by a few people that stuck with me all these years.
The first one I "go to thought" was more than one person is "awkward." Some even describing them "out of step, socially." Imagine a clock that is running fast or slow, but you have mentally compensated because generally, you can adapt depending on other clues. But they are always off, and you might have to warn others ahead of time.
Another comment was how autistic personalities are in that "uncanny valley of behavior" where people notice something is off, and it can be frightening but they are not sure why. Since autism is a spectrum of behaviors, which approach depends subjectively on the viewer. Kids, for example, can target autistic kids, and because they are developing socially, will group in "us" and "not us." Autistic kids are "not us," and the target of bullying. A lot of teachers know autistic kids just by how they are treated by others. "You're too weird," was something a lot of kids might say with developing language skills. The may not know WHY they hate a certain kid, but know that they DO. And "something is wrong."
Personally, I see autism as some kind of evolutionary response to a civilization that is growing faster that humans can compensate. In order to get actual insight, one has to be "out of step," lest they just end up trapped in the normal static of everyday compulsion. Like any other evolutionary advance, nature is "trying out" various things. Most will lead to dead ends. A few will adapt in other ways, and some will flourish in a new niche with new types of diversity. I have no proof of this, but I think it's more than "well, we define autism differently now." Yes, there were always people who were "touched by fae" or whatever convention was explained back in the day, but something has really changed. I personally think this and gender fluidity is a positive sign of things to come.