What two kinds of people do some people refer to? What two aspects of Lu Xun are chosen to show his greatness by contrast in poetry?

There are two kinds of people, that is, the proletarian revolutionary warrior represented by Lu Xun is one kind, and the author exposes and criticizes all reactionaries is one kind.

The poem adopts the contrast method, and selects Lu Xun's poem: (1) "Bend down to be an ox and a horse for the people"; (2) "Be willing to be a wild grass and wait for the underground fire" means that you are willing to dedicate all your contributions to the revolutionary cause to show your greatness.