Well, today i tried...changing...the objects section of raws. Well, it didn't end well. I tried to create a "Crazed Human" by copy-pasting stuff from the creatures, 'Floating Guts' and 'Elephant' as well as bits and pieces from others. I embarked to an old fort, but got tired of waiting for them to wander in. So the next time i created a new world (5 years history, pocket sized), and copy pasted my creature into all biomes (or thought i did), then increased their population to 100000:500000 (I have no idea what these numbers are). I use the "play now" thing then embark. I think to myself "well those numbers are quite large, i can't imagine it will take long to find some.", and not looking at anything else i wait for them to appear, none do so i decide to just make a fort and see what kind of stuff i messed up...thats when i realized...
I had no citizens. Instead i had 7 hydras with no skills except some military stuff and "Grand Master Observer". I can assign labors but they don't do anything. There were no positions for managers, militia commanders, etc. because my hydras were classified as Livestock, and had No Job after their name.
Tried a second embark with plan carefully, filled in skills then went to animals. Many of the normal ones were gone and instead there were wagons, wagons, nothing, chimera, centaur, centauress, nothing (male), and nothing (female), costing 1 point apiece. I get 100-200 of each and embarked but the game crashes, might have to use less next time.
Third embark, one hydra shows "fish" for a job, none of the others have any jobs. Then i get the message (name of hydra) cancels fish, TO INJURED, but has no injuries.
Finally tried adventure mode, instead of dwarves there are hydras, instead of elves there are sea serpents who can't get of of their trees. And instead of humans there are mermen and mermaids who drowned immediately after the game starts because the live in towns but breathe water.