Different organisms have come up with different solutions to the same problem, and because of that they can break in different situations. The 'service' they provide will be affected differently by an environmental shortage or excess. If twenty microbes are responsible for recycling organic matter and dust or drought or some chemical affects 10 of them, the others will expand to pick up some of the slack.

How the humans invented something so incredibly useful? Most probably after watching "useless" social wasps to mash bark to make its nests.

Aspirin occurs naturally in Willow bark; morphine and codeine from opium poppies; ephedrine and amphetamine is derived from Ephedra sinica (Ma Huang); quinine and it's derivatives from Cinchona calisaya; digoxin from foxglove (Digitalis lanata).

And botox from the bacterium Clostridium botulinum and related species has medical uses primarily for muscle spasticity conditions and migraines.

Aspirin is acetylsalicylic acid. It's also a prodrug of salicylic acid, but it has additional anti-inflammatory and anti-thrombotic effects, because unlike salicylic acid itself, it can irreversibly inactivate COX enzymes (enzymes that synthesize compounds needed for inflammation and blood clotting) by acetylating them. It's also less irritating to the digestive system.