Mothra wounded but did not kill Rodan. Godzilla did not eat Ghidorah - two of the heads he had burned up and bit the last one off - that is what he was mangling and then just disintegrated. In fact remember he literally put his foot through Ghidorah's torso while in Fire mode immediately before the last Nuclear Pulse (another throwback - the ability was introduced in Godzilla v Biollante).
I don't agree that the Russells were the center of the story. Emotionally Serizawa was. Kyle Chandler's character had anger with the Kaiju after his son was killed in San Francisco. But by the end of things he had made his peace and wasn't angry at Godzilla any longer. Yes Emma built the Orca that she and Kyle had designed earlier and yes she came off a bit like a virtue signaler for a bit - then she started to get what she had done was foolish at best and finally tried to fix it. Her arc made sense as did his.
I guess I did not mind having this family because they were properly integrated into the story and were not ordinary people caught up in the battle. That and Kyle Chandler is a much better actor than Aaron Taylor Johnson.
Note my take is similar to other Godzilla fan groups (DMan1954 et al).
We will agree to disagree on the family point then. . My main concern with them is that they might continue with their story in the next film. Serizara is gone, but both Kyle and Madison Russell survived. All I care to see in the next movie is Godzilla and perhaps some of the other monsters. No Russels or Joneses or Williams or any other new family. We needed a more scientist centered story with Serizawa in the center. At this point, we need a Monster Island and a soft-reboot of Destroy All Monsters since all of the kaiju are awake now. And the writers will need to be mindful that many major cities are destroyed and not just show them rebuilt after 5 years.