Africa is trying to get from zero to one. Its not surprising to me that independence after having all their institutions destroyed would not result in an immediate rise to prosperity. It takes leadership with vision and a distinct lack of selfishness to push a truly long term vision. I'd argue that africa is still reeling from cultural trauma. Fixing that is going to be difficult.

As far as import substituting industrialization. The devil is in the details. There are as many ways to do it wrong as to do it right. In many countries, its cheaper to buy a bag of onions from europe than to buy locally grown. Thats not right. I dont' have all the answers but some degree of controlled import-substituting industrialization needs to be done and informed by people who've spent considerable time studying the economy.

As a start, Europe could easly bring people from africa to study civil engineering, modern agricultural practices which they would then bring back with them along with financial assistance to bootstrap the very institutions that they destroyed. Expensive? sure, consider it reparations.