Marijuana was made schedule 1 close to 60 years ago, and it's very possible the people who made that decision had racist motivations. It's also possible they didn't and they just wanted to punish anyone who was using marijuana more than other drugs.
"People working at the DEA 60 years after this decision was made are very obviously racist and hate blacks and poor people" is much more of a stretch than "nobody really cares enough about this to change it and it wouldn't change very much anyway," isn't it? Unless, of course, you're not interested in actually understanding why things are the way they are and are more interested in perpetuating some victimhood fantasy.