How to quickly create a safe shelter
I just got the game yesterday, and while I'm dying and restarting a ton of times while attempting to learn the ropes, I'm having a really good time with it.
I've learned that the first thing I need is very clearly some shelter. I've figured out about pickaxes and doors by reading the beginners guide, but I'm not sure I'm approaching this correctly. Generally, to avoid a quick death on the first night out, I dig a cave and put a door on it. That has worked out okay so far, except for the one time I found a natural pocket filled with water and flooded my cave. Or when that same pocket started spawning skeletons.
This go around I have found a nice area to mine and built it in to a cave, but I just noticed sheep have spawned in the middle of the main corridor (I thought it odd that grass was starting to grow inside), so this has me paranoid that whatever horrors lurk in the night are going to start spawning in my house.
I also noticed I can't place my bed, so this is (in my mind) confirming my thoughts that this doesn't count as some place that is "safe".
So, I have very minimal supplies right now (or at the beginning of any game), how can I make something that qualifies as a house and won't get me killed?