Why does the polaris appear to remain stationary in the night sky when other stars show an apparent pattern?

Because one pole of the Earth's axis of rotation (the North one) points
almost exactly toward Polaris.

If Polaris had a pimple or a bump somewhere on its edge, you'd see
the bump rotate around the whole edge, like a clock, once a day.  But
the whole star appears to stay in one place, because our axis points to it.