The first Spider-Girl was for an alternate universe, Earth-982. The new Spider-Girl is for the mainsteam Marvel Universe, Earth-616. The mainstream Marvel Universe needs a Spider-Girl in it. I know the first Spider-Girl has more of a connection to Spider-Man, but Arana has spider-powers to and can do a great deal of good as Spider-Girl. Some comic fans have second thoughts about Arana being the new Spider-Girl, but, Arana being the new Spider-Girl is a good thing!