US has extraordinarily high number of prisoners per capita. Looking at crime rates alone, it does not have extraordinarily high levels of serious crime per capita. There's no way most people in prisons can be anything but innocent (or "guilty" of minor and irrelevant "crimes" pretty much everybody is "guilty" of and persecuted on legal system's whims). Unless you believe that young black men in US are the most criminal group in history of the world, most of them who are in prisons must be innocent by pure statistics.

This doesn't follow. You could believe that other groups have higher rates of criminality, but are underimprisoned relative to their rate of guilt.