Even before you get to the literal kilograms of bacteria, fungi and other fauna in our guts we’re a whole world unto ourselves.
We just don’t usually notice.
The fishes histories go back thousands of years. As a species it is super interesting... some evolved in hot-spring conditions that would simply cook most other animals. =3
Because there hasn’t been enough time and the ecological niche is non existent… ?
However… upon further inspection, one could argue that the micro biome is full of beneficial micro organisms that have evolved to fill this niche…
[1] Staphylococcus epidermidis
This is one of the most abundant and beneficial bacteria on human skin. It produces antimicrobial peptides and metabolites that inhibit the growth of pathogenic bacteria.
[2] Cutibacterium acnes
Despite its association with acne, this bacterium actually plays an important role in skin health by producing propionic acid, which helps maintain skin pH and prevents overgrowth of harmful organisms.
[3] Corynebacterium species
Various corynebacteria colonize the skin and produce lipases and other enzymes that help break down sebum (skin oils) and maintain healthy skin conditions.
[4] Malassezia species
These yeasts are abundant on skin and help regulate the skin microbiome, though they can sometimes cause issues in excess.
[1] https://en.wikipedia.org/wiki/Staphylococcus_epidermidis
[2] https://en.wikipedia.org/wiki/Cutibacterium_acnes