The Sea of Stars
Almost all races are capable of having offspring with each other. The results end up being either one race or the other, perhaps with a slight sign of their other parent (crazy haired dwarf for dwarf-gnome parents, human with golden-red skin with a dragonborn father). You can also have throwbacks, where a child is of a different race, despite both parents being something else.
Modifications to PHB races:
Human – Not default. Humans are known for their endurance, and diplomatic savvy, being willing to negotiate with almost anyone.
Elf – Live to 300 years, have a lull, where they do not appear to age for about 200 years, which occurs at different points in their life. Elves often have a love of the natural world, but this does not necessarily translate into a stronger connection with the fey.
Eladrin – formal name for high elves
Drow – Not, you know, hated and all that. May still be conniving and/or matriarchal, and/or okay with slavery. We’ll see here.
Half-elf – The only true-breeding mongrel race, Elf/human societies have them. Depending on how they identify, they may consider themselves half elf, or half human.
Dwarf – Consistently live to 100-150, generally attributed to their resilience.
Dragonborn – undecided
Tiefling – undecided
Orc – replaces half-orc. otherwise undecided.
Divided into two distinct tribes, the Gith are the manufacturers of airships, and all airships hold a Gith core. The Githzerai travel to spread their religion, and often aid the lands they visit. The Githyanki are often more willing both to negotiate and trade, but also to loot and pillage.
The Githzerai worship Zera, the consciousness of the entire sea of stars, and believe atunement with Zera is the only way to achieve meaning from your life. They believe that sailing the astral sea is The best thing to do, and believe they are the chosen children of Zera. They see anyone other than a Gith owning an airship as an abominations, and have been known to make suspect attacks.
Githyanki dislike their Zerai kin, but do enjoy their monopoly on airships, and while they may sell airships, they are at exorbitant prices.
Feared as legends on all shards, dragons are said to be the only species that can travel the void between shards by themselves, and can appear unannounced to conquer or pillage a shard. The threat of a dragon can unite even the most bitter enemies.
Other possible races
Kuo-Toa: Originating in Kali, information compiled by local historian Buana. Kua-Toa are found in deep underground caves in the depths of the oceans. Their society almost always revolves around the worship of a god however the god varies for each society of Kua-Toa. Their uniting factor is their blind faith which extends not to actual deities but often to Illithid, or Aboleths found in the underdark and the deep sea.
Sahuagin: Originating in Kali, information compiled by local historian Buana and Iman. Sahuagin were born into existence shortly after the Kimbirra-Trasin war on Kali of 2990 BKE. It is believed that they are actually elves who made a pact with a god in order to win their conflict and then dissappeard into the sea for millennia before returning to destroy their old enemies the Neotrasin. Sahuagin have since made their way through rifts in the Feywild to many other shards however still show their enmity for elves, and unexplainable ability to control sharks that was seen in Kali. They are universally reviled for being both evil and organised in their actions.
Merfolk: Originating in Kali, information compiled by local historian Buana. Merfolk were first believed to be sighted approximately 3000 years ago surrounding small islands near the edges of Kali however it is unknown when they actually transformed. True merfolk are actually humanoids who loved and worshipped the sea as their god to the point where they were granted the seas blessing in the form of gills and fins. While there are many rumours surrounding merfolk luring ships to their death, more accurate evidence suggests that most merfolk are no more benevolent or malicious than the humans from whom they originate.
Merrow: Originating in Kali, information compiled by local historian Buana. Merrow were created during the first demonic crusade approximately 2184 BKE. Merrow are merfolk who were transformed by the opening of a demonic gate in the ocean which permanently and irreversibly cursed them and turned them into violent, crazed, coastal scavengers. Despite the fact that they are often hunted by the Kali their numbers do not dwindle, however they also rarely attack in enough force to be more than a nuisance to the hunters of Kali.