That blacks are convicted of or commit more crimes does not in any way make it a fact that blacks have a predisposition to crime. Perhaps you do not understand the difference between correlation and causation. There are multiple possible causes for blacks to commit more crimes. It does not have to be inherent.
Lemme guess. It's the white man's fault, right?
Didn't say anything of the sort. Socioeconomic status and culture can drive criminality, it doesn't have to be due to race or caused by another race. It's possible that systemic racism could play or have played a part, but I wouldn't personally consider it the driving factor.
The point, however, is that there is no proof or even consensus about what causes people to commit crimes, let alone what causes people of a particular race to commit crimes. Therefore, saying that blacks have a predisposition to commit crimes is certainly not a fact.