So recently I decided to create a Star Wars D&D campaign. It starts out with the group as Mandalorian bounty hunters. However, before I make this officially start, I need to know if I can use other races for the players such as Zabraks, Trandoshans, Rodians, etc. Do Mandalorians consist of humans only or are there aliens in their ranks? If not, can there be aliens or will I have to think of a new start?
Choice of race will never restrict you in any way to play through any storyline in swtor.
As for story/lore/RPG i direct you to this wiki page.
"An interspecies warrior culture stretching back thousands of years, the Mandalorians live for one purpose: to challenge the greatest opponents in combat and claim victory, for honor and glory."
In Legends, Mandalorians used to all be aliens, comprised of the Taung.
Many different species later went on to join them.
Here's why you can't exterminate us, aruetii. We're not huddled in one place—we span the galaxy. We need no lords or leaders—so you can't destroy our command. We can live without technology—so we can fight with our bare hands. We have no species or bloodline—so we can rebuild our ranks with others who want to join us. We're more than just a people or an army, aruetii. We're a culture. We're an idea. And you can't kill ideas—but we can certainly kill you.
Prior to Grogu, we only ever see human Mandalorians.
However, it is never explicably stated that aren't any other non-humans and no one seems perturbed by Grogu's species.
In the end, it's your campaign. You can do whatever you want.