Coming from an experienced animator like me, It's certainly rough but you got potential. For a first animation it certainly ain't bad, you got some idea of good keyposing, expression, a sense of story telling and more.

There are certainly issues. Like here, the scene felt flat because you didn't try to make the character break out of a side on perspective like the dummy. And the slash is backwards (And the striking pose is a bit rough). It's just about refining it, learning more about dynamic perspective and incorporating that, making your poses stronger, and making your attacks more clear.

Keep chasing the potential you have. Someday, you'll make this spark of talent you have grow to a great blazing star. Don't lose sight of that. And hey, if you got animation works in future, let me know, I'll gladly give feedback on how to improve them. Goodluck with your future works of animation.