In the 40s and 50s the negro population of the rural impoverished and in places third-world-like south began to move North to the industrial areas that were needing workers. They were learning skills and some had the spark of the entrepreneur in them and struckout on their own. In short they had become the latest wave of immigrants and they were progressing as did the earlier waves from Italy and Ireland et al. Their economic conditions were rising and they were building families and homes. They were on their way to the Great American Middle Class. Then along came Lyndon Baines Johnson who showered money on them on condition that they do no work and do not marry. The rest is history. The Immigrant wave was shunted off into the ghetto-camps of the Welfare State, their progress aborted. People who are raised to welfare are not inactive. The girls get pregnant early and without any husband because that would diminish their welfare income. The boys, as they grow into men and unsatisfied with the welfare money strike out in the entrepreneurial path of the uneducated un moraled and setup businesses buying and selling drugs and women.
You’re background lacks one critical detail: The manufacturing jobs were leaving the northern cities. I worked with older blacks in the 80s who were bright, productive people - and their adult children were a mess (impacted much more by the job losses in cities). Even today there are some blacks working who pre-date the “Great Society”, and the contrast is night and day with younger ones (even those that are now 50 years old) in terms of work ethic, education, etc.; the welfare state was set up to head off an exodus from those cities as blacks would look elsewhere for work.