I've read Mein Kampf a couple of times. Uneven quality but it reflected the zeitgeist as well as helped drive it. Touches of badly misplaced resentment over the outcome of WWI - his "November criminals" were, after all, no more than the civilians left holding the bag when the Kaiser, Hindenburg, and Ludendorff skipped town. Overlaying that, a monstrous and pathological ego, pure paranoia, and a monomaniacal hatred of the Jews who were simultaneously supposed to be in charge of conspiratorial capitalism and Bolshevism, a pretty neat trick if you think about it. It's a real insight into interbellum Germany, invaluable for the student if a bit of a slog. It is curious that so few political leaders of the time - Chamberlain, especially, and Ciano and the entire French diplomatic establishment - could have missed Hitler's clearly stated intentions to strike east for lebensraum. Whatever else, we can't say they weren't warned.
It is also the tantrum of a child lost in its own fantasy world. Hitler conflates his own personal trials with those of his nation, the act of a narcissistic fool. Except for his army service he never once held an honest job in his life. There are a number of American politicians of whom one might say the same.
It is that.
And it is one of the most impactful books of all time.
As you said, it captured the interbellum zeitgeist.
And did so in both a elementary and brilliant fashion.
The man knew how to tune in to the passions of the people. Logic was just a plot device.
You nailed it.