Yes, XEL, you are right. We can also apply this to the heroes themselves. That is, any hero (Christian, Jelu, or any of them...) can be considered part of the highest caste of this world, regardless of their race.
Indeed, if you think about it, all the factions in this world can be considered part of one society. But only if you perceive their goals in a very general sense. If you look more closely, each race has different goals, and their self-preservation manifests itself in completely different ways.

That's right, we need to look at it in a general sense. Please give an example of what goals different races have and how they demonstrate self-preservation.

By the way, I didn't even consider the fact that there is also a division among the Lords. With humans, it's clear - their society, as already mentioned, resembles human society (our medieval one), but what about other races? Do they have a division of Lords into those who command and those who obey?

This raises an interesting question about power relations, which, as you know, are formed from subjects, objects, and power (the relationship between them).
Subjects: Lords. Only Lords. It is doubtful that one being would be subordinate to another (on the other hand, in Heroes 4, this is quite possible - and in principle, a stronger being must, by definition, subordinate the weaker ones).
Objects: Creatures, of course. But, considering the above, Lords can also be objects! And that is quite surprising. This subordination can be seen in the game itself: we choose one hero, developing him to the maximum, while the others perform supporting functions.
Power: power is expressed in management and strength (is there anything else - I don't remember). Lords manage because they either use force or are stronger. Sometimes management is based on feelings (Again, Catherine and her companions)