In what way are they trying to sell it like a Marvel Studios film?
Marvel studios films are generally fun with a lot of action and humor.
We know that the Fantastic Four don't get their powers until past the half-way point in the film, and we know there will only be a couple action scenes. We know that this film is an allegory for puberty in which their transition will be the primary story. It will feature cartoonish military officials who will stand in for parents and teachers as over-controlling oafs who don't understand the changes the teenagers are going through.
We know, from following this very closely, that the above is the real story and focus of the film.
But the trailers have been edited to make this look more like a Marvel film and avoid showing, in a clear way, what the film is actually about. The trailers take a couple action scenes and some mildly amusing moments and use those small pieces - recut over and over again and using slightly different varations of each - along with a shot of Sue laughing strategically placed after scenes that aren't particularly funny to act as a 'laugh track' and trick the viewer into believing they just saw something that is funnier than it was.
Try this experiment: "five minutes...maybe less." "...with a big-ass sunroof" "should I call the fire department?" Do any of those lines make you laugh? Of course not. They're not funny. But we see the same clip of Sue laughing after each one of those lines so, if we don't stop to think about it, we think we just saw something funny. There is very little that is fun or funny in these trailers, but the people making them are trying desperately to make people think they're seeing something fun and funny.
If you look past the editing of the trailers and commercials, you see a dull, flat, lifeless story with idiotic, childish theme of puberty, unrealistic characters and lots of cliche's. But the trailer gives the superficial appearance that this will be a fun, funny, action packed film - like a Marvel film.