Sweet Mother of Jesus I want to see this movie.
There are clearly several other monsters besides Godzilla as well. The flier, as mentioned, and then when the soldiers shot the flares up into the sky, that definitely wasn't a Godzilla-limb slamming down. It could have been the same flier, but the parts of the creature they showed before it would be a huge fucking flier, so I doubt it. And of course there is some huge skeleton, showing there was yet another one at some point in the past.
I sincerely hope this turns into a "Godzilla kills all the other monsters in the movie because he's King of the Monsters (figuratively, of course)" and then goes back under the ocean so there can be sequels, with more monsters and shit. Assuming this one is good.
The head has me sold for good now too, it looked great in that shot with the doors closing.