This is closer IMO to summarizing what Trump is about as potentially formidable general election candidate than ‘angry white low education racists’. Although I think you too are focusing a bit more in the first paragraph on the older story of why Trump could win the Republican nomination than why he could win the general election.
As hard as I know it is for solidly left leaning people to accept a lot of people are sick of ‘diversity’ as a club they are constantly being hit with, not necessarily actual diversity, though also that in some cases. It’s back to the Trump base of 40% of GOP primary electorate v. Trump support in 40’s or even close to 50 on his upswings in general election polls. The first is only a subset of the second, though a lot of pundits recycle the same pieces about Trump’s success in GOP side to explain why Clinton seems to have so much trouble putting him away, at least up to now.
Also a lot of general themes apply to why people don’t like Clinton, which is just as important or more as why they like Trump, since a whole lot of people don’t like Trump but are still choosing him over Clinton. She’s the epitome of a bipartisan establishment. Again, solidly left people might be very sure there’s no such thing, there’s the good guys and the evil Pubbies (which is where they actually agree with the partisan right except for who is evil). But a lot of people don’t think that way.
Trump can win if he sticks to how fed up people are with the way things have been going (the 70% wrong track), Clinton’s long attachment to the status quo (NAFTA, Iraq War, financial crisis at least in the indirect way of receiving so much money from Wall Street), and stay ideologically ambiguous. Once again, from solid left POV Trump is basically a Republican, Republicans are conservative, and conservatism is just plain wrong. But a lot of Trump’s vibes and noises (hard to call ‘issue positions’ exactly) have been pretty anti-Republican. That goes back to his success in primaries, where a lot of GOP primary voters had more hostility for the ‘GOPe’ than almost anything else. But in the general too, Trump is free to take various positions which aren’t particularly conservative, and sometimes broadly popular and where he has potentially superior credibility to Clinton (anti-free trade, anti-Wall Street, anti foreign intervention) as a practical political matter (forget whether he ‘should’) simply because he hasn’t been a fixture in politics for the last 25 yrs like she has, and it’s not an electorate yearning for the status quo. The 50-ish% favorable approval rating of Obama is often quoted as a counter point to the wrong track number, but Bill Clinton’s approval averaged a little higher through this time of year in 2000 and it was still apparent Gore was not being helped by the general feeling about ‘things’, even if people didn’t hold that against Bill Clinton personally in many cases. I think it’s the same here.
However, Trump doesn’t seem to be able to do this. He allows (or can’t help but actively seek) attention on himself, and he’s a very unattractive figure himself. He loses if the election is a referendum on Trump, as opposed to one on Clinton and the status quo.