Answers online range from “they don’t do much damage against netherite armor” to “use a shield” or “fight them with bow and arrow”. But you don’t start with any of those things and it can take a long time until you obtain them.
I mean right at the beginning, where you haven’t found any iron yet and therefore can’t craft a shield or armor. There legitimately doesn’t seem to be any reliable way to kill them without losing half your health. And they are EVERYWHERE. The only thing I can do is run away and dig a hole or pillar into the sky and wait until dawn, and if it’s raining even that doesn’t work.
I have no problems fighting zombies or spiders or creepers. But skeletons are like 1000x harder. What gives?
In my experience, iron is very easy to find early on in the game. Basically any cave I walk into has iron nearby, and if there is a skeleton you can block yourself in to hide while you collect the iron. If you don’t want to risk fighting skeletons in a cave without a shield, you can make your own stripmine, it shouldn’t take too long to find some iron