It really is short isn't it. There are a number of things that could be improved here for example the massive white background at the begining. But mainly I'd advice you to watch a few tutorials on youtube and then practice and try again.
Your right about it being short, but more to the point, in the future try to have your movies explain something or be funny or tell the viewer a story. In other words try to convey a point that you set out to make the video for in the first place.
Setting aside the lack of concept, this isn't a bad animation, I've seen a lot worse, and this being your first I can see you have potential, if you develop your skills you could get really good.
But for now, keep practicing.