Why does the speaker compare Death to a human in "Death, be not proud"?

Death is personified in John Donne's "Death, Be Not Proud" to show that it is not to be feared and can be conquered. The speaker opens with the idea that many have considered Death "mighty and dreadful," and the speaker seeks to dispel the power inherent in these beliefs. By giving Death very human-like attributes, it seems much more possible that people can actually emerge victorious over Death's limited, human-like powers.
The speaker calls Death a "slave to fate, chance, kings, and desperate men." Therefore, Death is not in control of people's lives; Death itself must submit to the power of kings—of men who are desperate for other options—and even to the whims of fate itself.
The speaker concludes by stating that Death swells with pride in erroneous thought, for after a "short sleep," people awake into an eternal life. Death does not even exist any longer. By contrast, the people whom Death sought to harm in life hold ultimate victory over Death, as they can never again be touched by its realm. These images all work together to personify death as a temporal and weak entity which should not be feared by mankind: who is ultimately more powerful in the face of spiritual immortality.