Race and class.

It is possible to play a charecter who defies all the rules and descriptions I've written, but it does make it harder for me to fit it into the world. In general, if you want to come from a township within Tariksan, your current knowledge of races from core dnd will be sufficient, as Tariksan is a very open nation with lots of racial mixing. The notable difference is a reduction in the natural lifetimes of elves, dwarves, and gnomes. Dwarves rarely live past 200, elves 300 gnomes 100. Hopefully you'll forgive my twisting of the rules, it makes timescales easier to think about.

Playing a race

I'd advise picking a more basic race, but am willing to negotiate. It's possible to play any race without any concequences (other than being very unusual) but sometimes concequences are fun right? My description of teiflings, assimar and changlings is a little odd, so know that the creator of these races has nothing to do with the life they lead.

Playing a class

As a player charecter, you are one of the "gifted". A person who's connection to the magical fabric is stronger than most (hence why you can do crazy stuff and get better so quickly), but you almost certainly don't know this in charecter, especially if you aren't playing a caster. There are guidelines on how the casting classes get their magic, but these are not cast in stone, it's my responsibility as a dm to fit whatever you want to play into my world. For example, you can play a cleric that I see as an arcane caster by my model, it matters not. If you are playing a caster I recommend reading the sections on the arcana. However, remember that your charecter does not nessicarily have to believe the truth: if they believe in an all-powerful creator god that's fine, they're just wrong, and they can still cast, I'll work out what entity would give them power and represent their god.