We orbit Sun because we called the star that is so important to our life "Sun".
That's actually not as silly as it may look.
Let's imagine we would orbit one of the other stars.
We would see a bright star at the sky during day.
We would call that star Sun.
Maybe the day would be a little longer, and the star a little more redish.
But we would devide the day into 24 hours, so the day would be 24 hours long.
I even expect that we would call the color of the Sun yellow, because the Sun is something important to living organisms that develop languages.
So, still orbiting that other star, we would discuss on the internet why we are orbiting the Sun instead of one of the other stars...
(See also Anthropic principle)
The Earth formed from matter near to the Sun, so it ended up near the Sun, and is orbiting it, because gravity depends heavily on distance to the influencing masses, such that oher stars have negligible effects to Earth's orbit. (see comment of @DumpsterDoofus and your reference to position)
To be exact, Earth and Sun are actually orbiting their total center of mass. But because of the mass difference, that is just above the surface of the Sun. The center of mass is called barycenter in this context and is useful as origin of a coordinate system to describe the orbiting movements in.
"We orbit around the Sun instead of one of the other stars."
is true because
"Sun is defined as the star which we orbit around."