Well this was pretty decent for a first animation, but there are some problems.
1. In some scenes, their was white showing on the edges of backgrounds. You should try to stretch out backgrounds a bit more.
2. It's kinda weird to have voices in this and yet still have text boxes. I'd recommend sticking with only one of them.
3. At 00:23, If that is suppose to be smoke, then you need to learn how to make it fade out instead of having it just stick there for the rest of the video.
4. There could be more animation in the sprites.
Just keep on trying, and you'll be a great animator. Good luck!