I checked your AI file. There are several problems. The first is that the Artboard containing the tree is only 60 X 120 pixels. That's just over 3.1% of an HD comp in width and almost useless for video. The second problem is that the two artboards are not properly lined up. You get better results if you delete the larger artboard. I found no problems at all by just deleting the second large artboard and importing the file as a composition retaining layer size.
I suggest that you work with an artboard that is the same frame size as a standard HD video and make everything a lot bigger.
If your final output is an Animated Gif, then that 60 X 120-pixel gif is going to be very small on any modern display. There are a lot better tools for creating animated GIFs than After Effects.