What is the Mitsvah mentioned at the conclusion of Bamidbar- mase? What do the travels have to do with the land and what does that have to do with the Levites, the tribe of Josef the Cohen Gadol and killers? Moses has only a few weeks to live and this is his conclusion of the Saga. Devarim is really a sermon, that follows the story. So in the conclusion one can find the essence of the whole narrative... according to common sense.
I challenge you to answer then, why you free prisoners when the Cohen Gadol dies, or how many people would actually kill someone by mistake without the use of a stone or even a piece of wood, in which case they were considered worthy of summarily being executed (a car accident leading to death would probably have been considered murder and not manslaughter). If you study Bedwin tribal behavior you might get an understanding.
Could it be that modern man doesn't have a clue of what the bible is talking about here? Could it be that reading the Gemarra isn't much help either because there are things so obvious they are not mentioned especially since the Gemarra was written under the influence of Roman and Babylonian law and the Jewish principles needed to be sheltered and defended vis a vis this foreign thinking.
Moshe does make perfect sense but I will only open the lock for those who actually care, the others will not pay attention.
When a person was dependent on land for survival, taking away his land or lesure to work it, was the equivalent of starving him to death. Involuntary murder was causing a person not to be able to work his land, chasing a person "sinnat Hinam" which is idol worship does this too but the slave driver/idol worshiper is blind and unconscious. The Levites didn't have this problem of owning land, but they had responsibilities to keep law and order and run the major cities and of course the "cities of refuge" and they also had large amounts of private property, and they too gave 10% like everybody else, and were responsible for collecting. Since our nation was holy and on holy land and this is proven by our journey in the desert and our survival by G-d there, land was never supposed to be sold and would go back to the grandchildren and great grandchildren for ever according to the number of mouths to feed. Therefore the "owner" of all the lands was not the King, but rather the High Priest.
When the owner would die, those that had "killed" subjects by disturbing the peace of a neighbor even causing him to die off his land (involuntarily!). These would be freed to go back to where they came from since they no longer had an outstanding unpayable debt to the owner, and they themselves after all were from the holy people.
The |Levites inherit from the fathers, but the tribe of Josef inherits from the mothers!
How does this conclude the whole Narrative? The tribe of Josef is the only tribe that receives the blessing of the G-d of Abraham Isaac and Jacob, so this is really a conclusion.