Yes, I am aware in the anime continuity, Godzilla evolved from plant-life. However, considering the anime movies didn't so much as touch upon that, I'm keeping the origin I'm familiar with. With that out of the way, let's begin
He stood among the treeline, towering over it like a mountain of flesh and bone, the sun glinting off his metal-like skin. Quite a lot had happened in the past few days. He bore the still healing scars from the beast from another dimension. It had been 20,000 years since he first came into existence. He remembered the day he was baptized in the flames of human science, his skin scorched and transformed into organic steel. Humanity scarred him all those years ago, but at the same time, they made him stronger.
Godzilla watched the setting sun with his bright blue eyes, now having gotten used to seeing its golden rays shine down upon the Earth ever since the trees of his kingdom blanketed it with their silvery pollen. His winged progeny rested on his jagged dorsal fins, seemingly watching the sunset with the creature responsible for bringing them into existence. All the while, their master thought to himself, remembering the day he finally entered the war between humanity and the other beasts who appeared as a result of their arrogance. He saw the damage both sides did to the planet, neither relenting. The moment the humans brought in the fire they used to turn him into what he was now, that was the final straw. If neither side would respect the world they lived in, they didn't deserve to live at all.
Then, after thousands of years had passed, Godzilla became the new caretaker of the planet, helping it grow and expand, hoping it would repair the damages done to it over nearly endless bloodshed. That is, until the humans and their allies from the stars returned to lay claim to their world... or rather, his world. It was only fitting he reminded them why they left in the first place. However, the moment the two alien races showed their true colors, in a way, Godzilla saved humanity from their respective abominations. However, humanity would have to be reminded of their place.
Earth was no longer their home. They were merely guests here. If they stepped out of line again, even for one second, they would be reminded once again why they were thrown off their planet in the first place. This was his kingdom. It always was.
As the last rays of light disappeared among the horizon, Godzilla, King of the Monsters, his head bowed, his bones popping as his massive body moved into a sleeping position. Godzilla's eyes then closed as he awaited the dawn of a new day.