It seems to me that the most distinctive feature is the save mechanic that essentially splits the game into levels where you can only save your progress when you reach a campfire.

For example, Jedi: Fallen Order is a soulslike because it has the same mechanic (with meditation circles instead of campfires), despite being SciFi themed. It does also have all those other things you mentioned, but arguably, so does Skyrim, which is definitely not a soulslike.