Eren just embodies the motto of "one man's terrorist is another man's freedom fighter".
I don't think the Reiss family actively hunted down everyone not controllable by the founding titan. There were a bunch of noble families (Eldians who are not subjects of Ymir, as Erigu said) who were not influenced by the founding titan and sucked up to the king so that they could rule the walls from within. Ackermans were opposed to the first king's ideology and so they became enemies of the royal family, hence their persecution.
I'm starting to remember now. The Reiss family tried to get rid of everyone that couldn't be controlled by the Founding Titan, so for all we know, there could have been a ton of different races besides asians and Eldians on Paradis at one point but they've all probably been taken out.
Holy shit.... that's fucking terrible, Isayama
I don't think the Reiss family actively hunted down everyone not controllable by the founding titan. There were a bunch of noble families (Eldians who are not subjects of Ymir, as Erigu said) who were not influenced by the founding titan and sucked up to the king so that they could rule the walls from within. Ackermans were opposed to the first king's ideology and so they became enemies of the royal family, hence their persecution.