I think it’s kind of the video game concept of “the final boss.” Every other enemy is lesser, you have to build up your strength in order to defeat Death. “The last enemy to be defeated” doesn’t mean “Death is the last thing you should ever fight” or “Death has the lowest priority of all our enemies”, but rather “Death is the ultimate enemy, the worst of all, such that when we defeat it our task is done.”
I think it’s kind of the video game concept of “the final boss.” Every other enemy is lesser, you have to build up your strength in order to defeat Death. “The last enemy to be defeated” doesn’t mean “Death is the last thing you should ever fight” or “Death has the lowest priority of all our enemies”, but rather “Death is the ultimate enemy, the worst of all, such that when we defeat it our task is done.”