Answer:
I am believed to be only one dimensional, and tinier than anything can be, and there are many who say that I am the basis of all that we see. What am I?
Fatherless and motherless. Born without sin, roared when it came into the world. And never spoke again.
Upon me you can tread, though softly under cover. And I will take you places, that you have yet to discover. I'm high, and I'm low, though flat in the middle. And though a joy to the children, adults think of me little.
A muttered rumble was heard from the pen, and I, in my walking stopped to look in. What was this I saw? A massive beast, hoofed, and jawed. With spikes upon its mighty brow, I watched as he struck the turf and prowled. And yet for all of his magnificence, he couldn't get out of that wooden fence.
He has one and a person has two. A citizen has three. And a human being has four. A personality has five. And an inhabitant of earth has six.
I will disappear every time you say my name.