The charts in here [0] should alleviate any doubts you had: when it comes to marijuana possession, blacks are indeed arrested at massively higher rates.
[0] https://www.washingtonpost.com/news/wonk/wp/2013/06/04/the-b...
[0] https://www.washingtonpost.com/news/wonk/wp/2013/06/04/the-b...
The publication "Homicide Trends in the United States" by the US Department of Justice has crime data broken down by race, for example. See pages 11 and 12: https://www.bjs.gov/content/pub/pdf/htus8008.pdf
The data shows that people of different races commit serious crimes such as murder at considerably different rates.
The FBI also publishes crime statistics aggregated by race: https://ucr.fbi.gov/crime-in-the-u.s/2016/crime-in-the-u.s.-...
Wow, why is that so high?
An attempt at a nuanced explanation (which undoubtedly misses a ton of factors):
Huge disparities in overall wealth and income, coupled with geographic segregation and isolation of a lot of the black population in areas of concentrated poverty, and the associated lack of access to social goods, such as public safety and good schools. The combined effects of poverty/segregation/isolation are specifically reflected in the fact that 78% of homicides involve people who know each other [1]. People who know each other killing each other is a result of the breakdown of community structures that would disincentivize that behavior. There have to be powerful incentives for someone to kill someone that they know, considering that the potential consequences are so severe (incarceration, violent retribution, etc). Often the perpetrators have very little (in wealth, community, etc) to lose, which also increases the incentive.
Another group that are similarly economically poor, Latinos, but due to a different history, have more intact community structures, don't have as high a rate of violent crime.
[1] https://www.bjs.gov/content/pub/pdf/htus8008.pdf (Table 8)
In all likelihood, higher arrests for marijuana of blacks are more due to the above factors than racism, though I’m sure that’s a non-zero factor as well.