That's actually normal, i switched mains a few times, I went from Jin, to Ragna, to Hazama, to Rachel. And after picking them up, i learned something new about the game mechanics, or how to beat the character, example, i learned that you could gatling, B,A,B,C in the air from using Rachel, and from playing Ragna i found out holes in his pressure strings, making it easier to fight him now with Jin.
It's also pretty common for people to switch back to their original mains after using other characters.