This film was set a long time before the Harry Potter franchise begun and so, as far as we can tell at this point, this really is mostly just the filmmakers seizing an opportunity to introduce this new story with a dramatic, explosive beginning. It also proposes a mystery, of which more is uncovered as the story develops.
It's only a moment, but to my memory there is a large, dark house, being approached by several official-looking men (MACUSA I imagine), and a white-haired man defeating them all quickly and effortlessly. In movie-language, this effectively presents us with our main villain, dispelling any curiosities from the very beginning that there may be some involvement by Voldemort, Tom Riddle, or other familiar character from the Potterverse.
As this film was always intended to be the first of a series of films, there are several unanswered questions. One being the imagery of this introductory scene (which in its nature almost feels like a flashback, or in the HP-world, possibly a vision or premonition), but also the Lestrange lineage mentioned briefly. There is plenty to uncover throughout this series of films presented initially within this movie, and I believe most characters met in this film will feature again in future to explore their stories and character arcs.
I firmly believe that this introductory scene will best be played out as a slow-burn mystery, only revealing the meaning of the scene in the last film of the franchise. The Harry Potter films have found huge viral success and has sustauined its longevity by having so many small, tiny, seemingly insignificant details uncovered for years after its release. To embark on a new movie franchise, appealing to the same fans, and set in the same universe, without featuring hugely overarcing mysteries and secrets, would be a huge waste of a long-set up ideology.