Oh lord no. Dent is basically Bilbo. Rincewind is a whiny annoying boring git with juvenile humor. Arthur could have been a companion to the Doctor or Gandalf. Rincewind not so much.
Dent is even more clueless and out of his depth than Bilbo, though, I think.
Dent is a clueless passenger through most of the books and all he ever really wants is a nice cup of tea and foir people to stop trying to kill him, whereas Bilbo yearns for adventure and gets it.
Dent <> Bilbo
All Rincewind ever wanted was to not get involved in adventures and, needless to say, he didn't get his wish. IMHO, Rincewind is at his best in Sourcery.