I think I pretty clearly suggested it was "new." A Jewish movement can be "new" and still be Jewish. Having said that, however, I should point out, that I think some of the cultural tendency of Hassidism are more particularly Hassidic than generally Jewish.
Have you forgotten that orthodox Jews opposed Hassidism? Ever hear of Elijah ben Shlomo Zalman? Isn't the only reason why the Hassidic Jews and Orthodox Jews get along today because of the threat against both from the Haskala movement at one time?
Not all Jews opposed the Hassidim. There were deep divisions among Jews at that time over them. Many supported the Hassidic movement as many did not.
The Haskala movement was indeed a unifying force among observant Jews. Despite the common rejection of the "enlightenment movement", there were deep divisions that remained well into the 1900's between Hassidim and their opponants. The primary reason that the "Mitnagdim" and Hassidim have reduced tension is that the philosophical differences between them has mostly disappeared. There is little disagreement on the original issues that separated the two sides in the first place.