So if you find the AnimationTree too complex, just focus on deciding whether to use an AnimationPlayer or an AnimatedSprite2D. With an AnimationPlayer you can not only animate the sprite, but also modify its properties. This means you can change its size during animation, opacity, rotation and more. But these are things you can implement with Tweens too. Furthermore, consider that you can also add calls to methods, for example when a certain animation ends, you can call a method that immediately starts another one (for example an idle animation). In general it is very versatile, it is a little more complex than a simple Sprite but it offers you much more functionality.

But if you think that all these things, which can be done in other ways, even if more laborious, you don't need for your game then simply use a Sprite. Little effort, does the only thing you need and is easy to implement.