Instead of using $race, use ${race}s
The {} is not normally needed around the variable name in a string if it is immediately followed by something that is obviously not part of the name, like a space.
so if $race = "Ogre" then
quest::say("$race"); prints Ogre
quest::say("${race}s"); print Ogres
quest::say("$races"); gives an error because there is no variable $races
Code:
quest::say("${race}s like you are better left dead than alive.");
quest::say("It's ${race}s like you who have ruined your own lands, You'll not ruin mine!");
quest::say("${class}s like you always bring out the worst in me.");