Unfortunately, not all forms of harassment or unequal treatment in the workplace are against the law. State and federal laws do not create a code of civility in the workplace. Rather, the laws are only concerned about when a person is harassed or discriminated against because of their membership in certain protected groups. What are those groups? It's against the law to harass or treat someone differently because of their race, gender, disability, national origin, military veteran status, or age (over 40 in most states). In those situations a person would have to show/link up the fact that they're being treated differently because of their protected group.
In other words, it's not against the law for the boss to be a jerk just for the sake of being a jerk. It is against the law -- it is illegal harassment -- if one is a jerk because of another person's race, gender, disability, etc.
Now, those are the law restrictions.
A workplace is entirely free to set up internal rules which more closely monitors employee conduct and says that certain "jerk-like" conduct is not acceptable and can result in discipline. However, those rules and that discipline are totally self-regulating to such a company. There's nothing that the law can do to enforce it.
From the facts you've described, this person is not breaking the law. So, your only option was to contact HR and see what they'll do. They have the discretion to do something -- but the law does not require it.
Good luck and best wishes for better days ahead. I hope that you find this information to be helpful in better understanding where you stand and why. I also hope that you find this answer to be ACCEPTable!