As always, things have to be done in moderation. I don't think it is a good idea to run multiple marathons a year and keep running 30+ miles per week for decades. You can run yourself ragged, or you can train and keep in shape smarty with plenty of cross-training mixed in. I also think that proper form and footwear makes a huge difference. (For decades hobby runners were wearing 3" cushions on their feet and heel-striking themselves into the ground).
In the US there are definitely more non-athletes with shot knees than there are long distance runners with the same. Of course this doesn't mean that there are only two choices (fat or run).
The OP was pointing out that running is the only thing we are really good at genetically. It is something that we haven't known for terribly long. I know that there were a lot of theories before why we have no coat and are bipeds. The running advantage certainly explains it.
I connect to my body when running in a way like no other exercise will allow me to. I also mentally connect to my roots in a profound way when I am hunting or spear fishing. One day I want to combine the two and go on a persistence hunt. Anyone coming?
G