Probably not going to be saying anything new here but we'll see.
Slide show, an animatic is used tell the story, getting a sense of timing and how motion is going to work in the final animation. As mentioned before , most animatics have key poses. Key poses meaning the essential poses/actions that tell the story , thus no in betweens. giving it a jerky motion. Your video is like a slideshow, as if you've taken panels from a comic and laid that out.
Art is too polished for animatic, animatics are just animated storyboards. Often is , if you look online of on the special features of dvds. You'll see that their animatics are just the storyboards pictures with the artist doing the V.O. Long story short, animatics are simple and quick, its not about the art.
Tips: depending on what program you used for drawing and editing some of this might be unuseable.
Well since this is a comic instead of using storyboards maybe try it with the already made thumbnails.
If you are drawing knowing in advance of it being used for a video, draw it in layers. If a character is the only one moving then it is not necessary to redraw the bg. (which you did at 0:44 but the idea can be expanded).
Or if the character moves right to left side of screen you don't need to draw a walk cycle, most programs let you animate pics around the screen. Simple motion like that can be left to the program, or move it frame by frame in ms paint and import that as frame animations lol. Work smarter not harder
Other than finicky stuff to make it "professional" there's not much else to say, good luck and try to research some online and see what you can learn from them.