Species
Brief
Most humanoid species share a common ancestor: a mammalian, thinly-furred, bipedal proto-humanoid. Evolved from this ancestor are fauns, satyrs, ipotanes, and humans. Evolved in conjunction with these, but not from any common ancestry, are nightlings and merfolk, by way of mimicry. Of all humanoids, fauns and satyrs are the most closely related, evolutionarily.
Terminology
There are a number of words used to refer to particular groups of humanoid species. They are used infrequently, but are useful for specifying who is being talked about.
Telluran
Refers to all non-merfolk, or in a more direct translation, those on the ground. Encompasses humans, satyrs, fauns, ipotanes, and nightlings. Used most often by merfolk.
Sunling
The Solan word for referring to all non-nightlings, though it doesn't actually tend to contain merfolk, so in practice encompasses humans, satyrs, fauns, and ipotanes. The term sunling was coined by nightlings in response to the term 'nightling.'
The Shotali equivalent 'zhaeshij' (literally light-people) was used before sunling began usage, but as nightlings integrated to the surface and began speaking and interacting in Solan, there was need for a universal language equivalant.
Seirim
Fauns, satyrs, and ipotanes are considered Seirims. They are equated due to similarities in form, ie: fur, hooves, tails.
Merfolk
Merfolk are, technically, made up of a few subspecies: Nix, iarans, and chimeraes. 'Merfolk' itself is, then, a group referring to all ichthyic humanoids, particularly nix and iarans, who have very similar cultures and interact with each other and tellurans regularly.
Shared Culture
The land is not sanctioned into segments, inhabited only by a single species. There is no seperation of the humanoids that populate the world, as such, there are some things that are more broadly shared. Certain aspects of culture are tied to locale rather than species.
Sailors
Along coasts, particularly in the south and east, there is a lively waterfaring culture. Ships sail to trade, transport persons, fish, connect with abyssal merfolk, explore, and faster transport goods. Sailors vary from wildly respected to begrudgingly tolerated, but all agree in the necessity of their work.
Sailors are broadly categorized into one of two sects: tradesmen and pirates. 'Pirate' is a broader term than what we may assume, encompassing explorers, travelers, some ferrymen, and, yes, criminals. Tradesmen are those transporting goods, fishing, and transporting passengers. Because of the differences in how their jobs require them to interact with each other, the sea, and those onshore, and to advertise their trade, sailors pierce an ear. An ear, because which one varies. Tradesmen pierce the right ear, pirates, the left.
This tradition began, and still has its roots in, a contingency for death at sea. Seafarers get gold or silver earrings so that, in the event they die and are washed ashore, there is payment for a proper funeral. Many human and satyr sailors- to which the legacy of a name matters greatly- will get their name engraved on their earring, usually on the inside of a loop, so they are not buried nameless.
The number of earrings worn, regardless of if the wearer is a trademan or a pirate, indicates a sailor's status. Captains have three piercings- all in the same ear- to make their authority known. First mates pierce their ears twice- more authority than a normal crewman, but less than a captain. Crewmates get only a single earring.
Mercenaries
'Mercenary,' like pirate, is a broad term, encompassing everything from dragon slayers to to hunters to bounty collectors. They began as monster hunters, more specifically, dragon hunters.
Dragons and griffons alike, like many wild animals, especially ones that reach the sizes they do, can be dangerous. There were always the hunts that existed for renown, for sport, but they began- and usually remained- the result of an animal that strayed too close to a settlement and started causing problems.
Post-cataclysm especially, when it was harder for everything to survive, large dragons and griffons would venture into humanoid spaces to find food. Livestock, pets, and, yes, the humanoids themselves. Dragons and griffons are animals. They will find food where they can. The large ones especially don't have a reason to not prey on humanoids, not really. If they're available for hunt, they will be hunted. Humanoids are not the top of the food chain. As a result, towns, families, individuals that were threatened by the habits of these creatures would call for a hunter, a knight, a mercenary. To get rid of the problem.
It's a dangerous but respected position. Few hold it, but the ones that do are treated accordingly- you never know when you may need one. Eventually, guilds form. Groups of mercenaries, usually with similar targets, that aid each other, teach others, travel together, etc. Previously, to be a mercenary was to be alone. Now it doesn't have to be that way. Some still are, but that's also because it's the kind of work that calls to those who seek solitude. Some guilds are familial, some are more akin to a job. There is infinite variation in how they present.