the length and influence of colonialism is overrated. The problems that came after are largely African made but a natural result of how complex-ed the reality at had was. The whole 'europe stole all their resources' thing is largely BS, though every true in isolate cases. Colonialism was horrible in the Congo, which you can read about yourself, and europeans were all about stealing historic artifacts and underpaying labor or not paying them at all. Otherwise colonialism was a pretty short stint, and once 1 generation of africans had received modern education they were motioning, successfully, for independence.
Colonialism it's self was 2 generations long, though european involvement had extended past that. Of course the experience of all countries were different, but for the most part colonialism's biggest legacy was creating artificial nations and overt political involvement that encouraged corruption.