If animals eat each other daily and defecate, why don't rainforests and the natural world smell like rotten corpses and feces? Wild animals don't have recycling people.
Herbivore faeces doesn't smell as much as human faeces (or dog/cat/other carnivore). The vast majority of mammals, by number or mass, are herbivores. Population densities of large herbivores (overall - we often go to see them where they gather in large numbers, but they don't spend long in one place then, or they'll run out of food) are much lower in the wild than in even free range farming, so there just isn't that much to smell.
You can smell rotting meat in the wild, on rare occasions. Usually it's scavenged before you get the chance (again, given the numbers, deaths are fairly far apart). I've only smelt it very close to a kill or where the wildebeest migration crosses the Mara river in Kenya. So many are killed in the crossing that the scavengers can't keep up, and decay happens fast in the heat. The bits that get eaten don't smell until they come back out again, much reduced in volume. Some carnivores bury their faeces, but others mark territory with it or use latrines (you'll smell those if you're close). To a decent approximation all carnivores will scavenge given the chance - it's free food - so corpses don't hang around for long. Even with few or no large carnivorous mammals flesh from an accidental death is dealt with pretty quickly by birds (corvids in many places, vultures or kites where they're found) or insects. Roadkill is reduced pretty quickly even with steel predators thundering past. Bones themselves don't smell.