Before creating a character in Defiance check out this character creation guide video made by Grimwyrd (like and subscribe!) that explains the all the things you have to know and could miss.
There are some character options that are kind of hidden and you could totally miss and also there is the question of which starting class should you pick.
The origin choice is a cosmetic one and does not have an impact on how you will play the game. It only gives you a different starting outfit and secondary weapon. You can choose from a Veteran, Survivalist, Outlaw and Machinist.
After making your character you are ready to start playing and killing some bugs!