I think Forrest Gump's major quality is an indomitable spirit and an ability to overcome. (War Hero, runs across American, gets the girl)

I'm not so sure it applies to Arthur Dent, who tends to roll from one situation to the next. There is resolve, but it never really rises above.

I think there is similarity in the storytelling, that both characters find themselves in extreme situations, and somehow navigate them despite their own limitations.