The movie is meant to be showing these people in the days AFTER they were famous. Alan Quartermain for example is living in Africa in retirement.
One item I found pretty funny is that the Invisible Man is not THE IM. The movie producers were unsure about the rights to the H.G. Wells character, so this is someone who stole the formula.
They did a good job with the characters, and I LOVE the job they did on the Nautilus! Everything is bigger than life. Remember this is not meant to have any basis in reality and you'll be fine!