The player character does have dreams about their life, which are shown through text when you sleep. Some of these reference your death, but are more statements of fact than a PTSD attack
You drink mead-based potions, but you don't get intoxicated or addicted or anything like that. They just give you poison-resistance, or cold-resistance etc.
There are sea serpents in the ocean which can attack and potentially kill the player or destroy their ship or be slain themselves.
However, the sea serpents look more like seagoing dragons than like true snakes so that might or might not be an issue.
One of the more recent updates to the game added a new area which is predominantly populated by insectoid creatures similar to ants, ticks, and other bugs. As part of exploring this area, you will have to go into the nesting areas of said creatures, the environments of which can be very unsettling and creepy.
Not "on-screen" as it were but the glowing blue eyes of a particular kind of creature are commonplace crafting ingredients. The eyes are not especially detailed or human-looking but it's worth considering.
There is stylised bright red blood when a creature (or player character) is injured or killed. When enemies die, many of them drop various body parts and objects which can be used as crafting materials but it is not overtly gory or caused by battle wounds or the like. Entrails, eyes, heads, fangs, among others are some of the body parts that can be gathered from slain foes.
The game's graphics have a more fantasy/stylised aesthetic so it isn't photorealistic but if you find body parts and the like icky, it might be best to steer clear.