You're right, partially. Part of the problem lies in the ideology and jurisdiction of ICC. War crimes and crimes against humanity are very broad terms and the court does little or no attempt to explicitly define these crimes. Plus, I don't think ICC recognizes terrorism as a crime yet, a term used for almost all modern crimes. Cases of civilian deaths in Gaza, Iraq and Afghanistan ought to bring state sponsored terrorism in the equation as well, which is always be denied.
Secondly, the court brings political leaders in the box, which is hypothetically a good check on all those who rule. Still, in order to be able to prosecute, ICC needs to bear the risk that the people won't oppose its decision. Majorities would rather have national courts punish their own. The same reason we wouldn't want to hand over zardari. Ultimately, its the sovereignty of National vs. International courts. Now an organization which has absolutely no practical jurisdiction of its own and is dependent upon UNSC to refer cases is bound to malfunction. Come to think of it, i wonder who has the power to legislate in ICC. Anyway, I don't think it racism per say. Just that the Africans are easiest to blame and ICC needs to do something in order to carry on its existence.