An old Idea

Way back when, at the end of the ninth grade year, before summer started, I came across an Idea while looking up at the stars. I was wondering what separates us from animals. Though it's slightly assumptive to say, I believe we have a higher understanding of the things around us, when compared to your average dog or cat. So then I questioned what is below a dog, or animal? An insect? Then below that perhaps a cell. I continued this train of thought till the idea that perhaps there is a simple sense of existence, the bottom rung of this ladder. You feel, not in the traditional sense because a table can't exactly interpret stimuli, but you have a sensation of existence. What do you think of this idea?