In simple terms, people believe what they want to believe, and it's typically very difficult to change that.
That's absurdly, completely, insanely wrong, and yet you've chosen to believe it. At the very least, you haven't checked to see if even makes sense.
The surface area of the earth is about 200 million square miles, using this formula: area = radius squared x 4 x pi.
Now, what is '1/6th trillionth' in your statement? Is it '1/6th of a trillion' (which is about 167 billion), meaning 1/167,000,000,000 of the earth's surface is populated by humans? Or is it '1 sixtrillionth' 1/6,000,000,000,000, meaning 1/6,000,000,000,000 of the earth's surface is populated by humans?
For your sake, let's assume the former. In that case, humans populate an area of about 200,000,000 / 167,000,000,000 miles, or about 0.0012 square miles. Do you still want to believe that?
If you want to say something intelligent about this, you first need to define what 'occupy' means. Does it mean how much land area our bodies occupy? If so, is that standing up, sitting, or lying down? Does it mean how much land our cities, farms, and other modified areas of the planet occupy? Decide.
Actually, you should first decide if such a comparison even matters. A single volcano with a relatively small surface area can influence climate over the whole earth if it erupts endlessly, as human activity in general has been doing for centuries, and human industrial activity has been doing for decades.