Mein Kampf is a pretty poor source to understand the roots of fascism. People have this idea, that Hitler was some elaborate writer, who laid out a comprehensive and enchanting piece of work, that was then surrounded by mysticism.

You don’t understand the roots of fascism from books written by fascists. You understand it from looking at fascists in action, both on the side of agitators and those following the agitation. And the roots are pretty simple: Combine fear with hatred and an inferiority complex, mix it with simple solutions and by elevating individuals of the in-group by terrorizing the out-group.