How are you supposed to heal?

[Wintermute]

I'm only an hour or two in but the slimes keep killing me because I can't find a way to restore my health.

[Mackenzie]

Cooked food usually does the trick.

[Phara]

collecting a fairy heals and the quest of the fairy queen helps too

[Myst]

Early game cooked Fish is pretty easy to unlock.

[X-Death666]

Meat