Character creation for the Cosmic Seas setting is unchanged from those of core D&D. Given the large multicultural nature of the Dragon Empire, just about any race could be encountered in a star port, so GMs are encouraged to allow races from any setting supplements they feel comfortable with. All of the races in the Player Handbook are expressly allowed.
The official language of the empire is Draconic, and frequently spoken by dragon lords and their dragonborn servants. It is the language of rulership and law. “Trade tongue” however, is the most frequently known language in the empire, and is essentially the Common language from the PHB, p123. For characters from the Draconic empire, the Draconic language can be treated as a Standard instead of Exotic language.
Notes on Backgrounds
Acolyte: The Celestial Church is the most common religious pantheon in the Empire. Characters can choose to serve the church as a whole, or be devoted to one the Nine in particular.
Guild Artisans: Shipwrights and Sailmakers make for highly useful backgrounds in the Draconic Empire.
Noble: Dragonborn nobles may be associated with one of the Metallic Houses or Chromatic Clans of the central core of the Empire. Other races as nobles likely hail from the subject kingdoms whose families rule a few planets but are themselves subject to the Emperor.
Outlander: You either hale from a Grounder world, one that has not been brought into spacefaring society, or from a world outside the Empire’s borders.
Sailor: Instead of an ocean going nautical sailor, you could a starship sailor. You have proficiency with Vehicles (Space) instead of Vehicles (Water.) Similarly, the Ship’s Passage feature applies to starships instead of ocean going vessels. This is highly useful if the character do not have a ship of their own, yet.
Pirate (Variant Sailor): The Black Star Confederacy is a region of space ruled by space-pirate fleets, but smaller space-pirate operations can be found in many corners of the empire.
Soldier: This background works best if military implied is the Draconic Empire’s legions. The Draconic Empire is famed for their Dragonborn Shock Troopers, but the Legions are not picky about what races they recruit, especially as part of the new emperor’s conquest of the fringe worlds. The legion has grown considerably in the last 99 years, and many veterans cut their teeth pacifying grounder worlds.
All of the Common and Uncommon races in the Players Handbook are available for play. Other races are available for play and can be chosen from the Adventure League playable races list. Of particular note for my games, Kobolds, Orcs, and Tortles are numerous in the Dragon Empire.