Who is Rincewind the Wizzard from The Last Continent: A Discworld Novel and what is their importance?

A recurrent character in Terry Pratchett's Discworld novels, Rincewind (no first name given; indeed, Rincewind doubts if he has one) has just survived harrowing adventures on the Counterweight Continent of Discworld in the novel Interesting Times and, rather than being plucked back to Unseen University (UU) in Ankh-Morpork by the Hex computer, he is, through a glitch deposited on Discworld's last continent, Fourecks. This is an unknown continent near the edge of the disc that resembles, geographically and culturally, Earth's Australia.