This is an interesting set of questions, for sure. I am wondering if you mean "scenes of moving and departure" as literal or figurative. I will take one of each so that I can cover all of the bases for you. The most important literal movement and departure is from the South to the North while an important figurative movement and departure is from religion to atheism.
First, let's discuss the most important literal movement and departure in Wright's book: the move from the South to the North. Wright considers the move from the South to the North as an exodus away from racism. Consider Wright working as a young teen in Memphis, Tennessee.
The White South said that it knew ’n*****s,’ and I was what the white South called ’n****r.’ Well, the white South had never known me—never known what I thought, what I felt.
Here he witnesses the same kind of racism and violence as in other Southern towns and longs to move north. His choice is Chicago, Illinois: an unknown. This departure to Chicago definitely represents his escape from racism. In this departure, Wright learns that the North (and specifically Chicago, where he is bound) holds as much freedom as he can find. We see Richard Wright speeding towards Chicago by train at the end of the book.
Secondly, we have the figurative movement/departure of Wright from religion to atheism. Wright's young life is full of experiences of "Christians" who both beat him and degrade him. This leads Wright to believe that Christianity as a whole is completely false. Further, Christians are, at best, hypocritical in not practicing what they preach. Ironically, Wright does get baptized, but only because he is badgered by his mother. This movement/departure away from religion represents Wright's move from idealism to reality. Sadly, he learns that religion, and especially the Christian religion, is not for him.
In conclusion, even Wright's departure to Memphis as a young teen is another departure. That one represents his move away from childish ways and into adulthood (where he will work for his living). In that move, Wright learns that anywhere in the South will breed racism and violence.