I think the average knowledge of the stock markets and investments in general may be pretty low, and often wrong. I have some knowedge and experience, but I don't by any means claim to be an expert.
Yeah, I'm by no means an expert. But this has been a frequent topic of conversation as my son is 16 and he's got some interest in it, and my 11 yo daughter is copying his interest as well.
At the start the biggest thing was (and maybe still is with the 11 yo) getting them to understand that popular companies aren't always good stocks to own. (Sometimes they are, of course). But just Saturday we were in the car talking about it and my daughter was saying "Starbucks is probably a pretty good stock, they're everywhere". Maybe it is, maybe it isn't, but that's not how you determine it. In the past they've brought up Disney, b/c obviously being kids, they're in the age (or used to be for the oldest) that they think it's a good company. But (as we all know given some of their issues as a conglomerate) that doesn't mean it's a good stock to own. There's a lot of risk regarding their future business plans. Tesla is another that my son brought up because he thinks the cars (absent the Cybertruck lol) are cool. But the company is valued as a tech company (high PE ratio), not an automaker (low PE, moderately decent dividend yield), and at some point that's going to be a problem for investors reconciling that IMHO.
With every stock, you need to assess the state of the business it represents. You have to understand how they make money. You have to understand how you expect to make any return (share price appreciation, dividend, maybe both). And that includes obviously predicting things like growth/contraction, market share growth/contraction, what the other companies in the sector are doing, etc.
Or you could just assume that everyone expects every stock must have perpetual growth and that capitalism, based on your lack of understanding, is fundamentally flawed as a result.