OCs and non-fandom always get virtually no attention though. And sometimes if I draw something for a different fandom than usual it attracts lots of non-followers? but idk
I actually gravitate towards originals myself but that's what makes art so fun! Everyone loves something different and what speaks to one person might not work for another.
I've actually never used tumblr but there's probably something to what demographic you'll find there as well.
I say do whatever makes you happy and like-minded individuals will eventually find you!