I've had characters who were kind to one person and absolutely terrible to another. I think in a world with such loose morals (no real universal moral compass or religious moral compass), someone can dip their toes into both spectrums without being a hypocrite. So, i'll have my rough and tumble ranger who's got a soft spot for kids, because they remind him of himself. Or i'll have a Noble who is an absolute turd to Commoners but has a fascination with a certain tribe, so he's actually genuinely 'kind' to them.
So yes -- I do think there is kindness in the world. While your PCs might wish to be kind to everyone, they would likely find out in their past (or they will find out through actual play) that there are people out there who will -not- be kind to them, despite anything they attempt to appease them. These people may even have enough power to harm them, or even have them killed. It could be -because- they are kind, that these people wish to snub them out.
It evinces cowardice from the powerless, and stalwart indignation from those that wish to make a stand. So pure kindness, unadulterated compassion, I think is really rare in Zalanthas. I think it typically gets bred out of you as a kid. You are born innocent and without the 'stains' that come with aging, but in a harsh place like Zalanthas, you would learn very quickly that true kindness is a weakness that others exploit. So, actually, i've seen that very sheltered people (some tribals, or middle-class Allanaki) tend to be much more kind and naive, because they are less experienced with the world as a whole, or have less of a complete understanding of their place within it. People from the Labyrinth, or the 'poor caste', are usually quite familiar with their place in the world, and understand that kindness is typically a way to disarm you into making a mistake. There's a reason Elves have 'Tests of Trust', and it's mostly because they are constantly paranoid that people are attempting to take advantage of their trust, so they guard it with a chastity belt.
I suppose, in closing, just keep in mind you shouldn't make a PC that's kind for the sake of being kind, because you enjoy being kind IRL. Just as well, you shouldn't make a PC that is cruel because you enjoy being cruel IRL. You should make a PC where it makes sense for them to be kind or cruel, based on their personality, background, and outlook.