It depends on how complex your animations are.
If just have a few (i.e. idle, run walk, jump) then you can use a Sprite with an AnimationPlayer or just an AnimatedSprite.
If your animations are more complex (i.e. holding items, various emotes) then using a 2D Skeleton will make more sense. 2D Skeletons are a lot of work to make so you only want to use them when you need to.
In my opinion, 2D Skeletons are a "you know when you need them" situation. I start with basic animations. If while I'm planning them out I realize I'm making a ton that could be covered by individual pieces moving, then I'll create a 2D Skeleton for that sprite.
The best example I can think of is when your character is holding an item. If you only have one or two items, it makes more sense to create separate sprite sheets of your character for each item. If you have a lot of items, it'll be less work in the long run to create a 2D skeleton for your character. Then, you would only need to animate the hand/arm of the character.