I'm a returning player who has not played the game in several years. I created a new account since I was unable to find my old one. I went to create my first character and all but 4 species are locked. I'm a paid sub. Why can't I chose any species I want? I don't remember this limitation the last time I played.

They have always been locked.

But if you play a species to level fifty (starting at level one, naturally), you unlock it for all origins. For Zabraks, that unlocks both colours of Zabs for both factions rather than red=Imp, brown=Pub.