[naive_subseed]

Your list so far:
Necromancer: dead
Elf: fancy humanoid
Sahydon: water inhabitani
Minions: faceless
Human: regular

The first thing i'd suggest is that you somehow put all of these creatures in juxtaposition with each other, a fancy way of saying show how they interact.
-Maybe the elves are like an evolution of humans and were hunted down before they built their own society. Maybe they just are arrogant assholes who were adored by humans for their crafts and therefore feel above them.
-Necromancer could work, but i feel zombie is a shallow way of putting it. if they are dead, maybe they can only be killed with violence so that they are cursed to a bloody death. in the end, they are people who are free from the constraints of society. Will they begin their own world anew or try to reclaim their own lives back? i don't know.
-The water creature first make me think of environmentalists yelling at the human world for being so materialistic, but i realized Sahydon sounds like satin when i say it in my head. SO maybe they are moralistic in their view, but cause destruction and chaos to get their way.
-With Minions mass production is the key. i know myths where people are made of mud and dirt, and it is easy to make them and depending on the quality of production, easy to break them. think either a natural process of creation being corrupted, like a virus. Or think of workers creating these monsters, like a sweatshop.
-Humans are always humans. war is always war.