After reading some negative Steam reviews it appears to me that people are dying too often from sheer inexperience and not enough combat practice.
That's a good point.
You can't expect new players to know that they have to play this game differently. In any single other game, when you see a meaty, mindless undead slouching around, the response is "zombie : fight it until dead (again)". Here, it's actually a pretty bad strategy for a new player.
The idea that you can bypass them if you're careful, that they aren't necessarily aggressive or that you should run away and lock them behind doors, that simply won't come to the mind of most players. Decades of game, movie and other media experiences taught otherwise.
What would help a lot, here, would be to show that through the first gameplay.
For example, the first "zombie" you meet is put in such a way you are incited to
ignore him.
Maybe it is in the starting room, in its corner, pacifist until you hit it. Most players won't try to attack it until they got weapons, so it will give them time to realize it is not aggressive.
And given the weapons you find at first, attacking it will kill or maim the ones trying it nonetheless, teaching that you shouldn't mess with them unless necessary - without too much of a cost, as you waste almost no progression.
The best tutorials are done that way: transparent, teaching through the game situation itself and how players react.
Some lore to tell how they don't like being watched, and other rules someone observed on their aggressiveness, would also help later.