Jin in Japanese means person. When Adressing race names in japanese u put the -jin kataliksis so if u want to say someone he is hylian u say Hyrian-jin! (japanese have them same letter for "L" and "R")
I'm just sayin, but there's no "jin" in "saiyan". I think some idiot made that up and put "jin" in the middle of the word "saiyan" because in the English version of DBZ, Buu pronounces "Super Saiyan" wrong and says "Super Saiyajin" instead (because he's a baby and he can't pronounce things the right way). And the problem is, most people accepted the "jin" in the name and now, "Super Saiyan" is usually abreviated with "SSJ" instead of just "SS".
I'm just sayin'.