If I may, I do think you left out one important point. While the moral law does impose duties on people, in doing that it establishes protections for all.

Kant realized that the only legitimate moral constraint is one that a person has willingly placed on oneself. Otherwise, it must have been imposed on that person, one way or another. That would violate the ‘autonomy’ that every human being has by virtue of one’s possession of a separate, independent will of one’s own.

So his task was to arrive at a moral law that every human being (every being with a separate, independent will and a rational capacity) would necessarily have to accept for oneself, such that to deny it would be to engage in an intentionally irrational action. To do that would be to abrogate (or abdicate ) one’s humanness. To do that is (in Kant’s construct) to remove oneself from the protections of that moral imperative.