"It's not personal" is not a useful thing for the HR person to say. Sometimes what's okay for one person is not okay for another. The point here is the boss crossed YOUR boundaries on how you want to be treated. You get to have those rules as a human being, whether or not you're being paid within a hierarchical workplace. That being said, it doesn't sound like this is a workplace that has the capacity to support you or address the issue. Perhaps ask if there is any mechanism in the workplace for employees to give performance reviews to bosses or ask for how they want to be led. Also is there access for managers to training on people-first management?

Meanwhile, you can work on your own assertiveness and emotional activation. "It's not personal" is dismissive. However, people do tend to be shitty because of their poor emotional regulation and communication skills. In that sense, it is a "them " issue, not a "you" issue. You can try to have useful thoughts about the manager's behaviour like "My wellbeing being doesn't depend on my manager" -- but none of that will change the fact it's not okay to mistreat employees.