According to Britannica.com, “[It] is the brightest star that appears nearest to either celestial pole at any particular time. Owing to the precession of the equinoxes, the position of each pole describes a small circle in the sky over a period of 25,772 years. Each of a succession of stars has thus passed near enough to the north celestial pole to serve as the polestar. At present the polestar is Polaris (α Ursae Minoris); Thuban (α Draconis) was closest to the North Pole about 2700 BC; the bright star Vega (α Lyrae) will be the star closest to the pole in AD 14,000.
“The location of the northern polestar has made it a convenient object for navigators to use in determining latitude and north-south direction in the Northern Hemisphere.
“There is no bright star near the south celestial pole; the present southern polestar, Polaris Australis (also called σ Octantis), is only of the 5th magnitude and is thus barely visible to the naked eye.”
Think of the Earth as rotating on an imaginary line that is tilted, not vertical.