Could Carol Danvers, Captain Marvel, still be considered an Earthling?
No.
It should be said...
Was Carol Danvers still human?
The answer was no.
After Carol Danvers absorbed the power of the Cosmic Cube—the Space Stone—her lifeform had already been elevated. Rather than calling Carol Danvers human, it would be more accurate to say that she had become a god.
Gods had ranks as well.
A lower god and a creator god were both gods, but a thousand lower gods combined still would not be a match for one creator god. Similarly, a thousand mortals together would still be no match for a lower god.
Carol Danvers had not built herself up one step at a time, laying a solid foundation as she rose from mortal to god. Instead, she had suddenly climbed to a lofty position and ascended to godhood in a single bound. Naturally, her mindset had undergone a complete transformation as well.
Not to mention...
Carol Danvers had once lived in the Kree Empire for a period of time.
It was like some exceptionally idiotic reality show from his previous life. If a child from some impoverished backwater had witnessed the brilliance and prosperity of the Great Cosmos, would they honestly return to their hometown—a tiny village so isolated that it did not even have a highway leading to the city—and pretend none of it had ever happened?
Perhaps some would.
But Carol Danvers was absolutely not one of them.
This could already be glimpsed from the original story. In Carol Danvers's heart, Earth was no longer particularly different from any other planet.
Returning home in glory, benefiting her homeland, bringing advanced technology from the universe to Earth, and helping those who had yet to become rich?
Hah.
Among all the capitalists in the Federation, one could