> debt requires violence
Any kind of property requires violence to exist. If I say "this is my land" and you disagree, the only way I can enforce my claim is through violence. Debt is just a specific case of a general phenomenon. (This applies to communal property, too.)
> Before the US destroyed Libya, it had the highest GDP in Africa
Do you have a source for this? I see Libya's GDP circa 2005 at $41 billion (in 2005 U.S. dollars) [1]. South Africa's 2005 GDP was $260 billion in current U.S. dollars [2] (bit over $200 billion in 2005 U.S. dollars [3]).
[1] https://en.wikipedia.org/wiki/Economy_of_Libya