Are the Humans of the Empire truly Human?

This question came to me while reading the book Prospero Burns. In the book, it mentions a Human Civilization, technologically more advanced than the Empire, called the Olamic Quietude, which did not consider the imperial humans to be true Human Beings, and even claimed that the imperial humans were the creation of some alien race.

Excerpt:

During the second of these skirmishes, the Quietude managed to capture the crew of an Imperial warship. The commander of the 40th Imperial Expedition Fleet sent a warning to the Quietude, explaining that peaceful contact and exchange was the primary goal of the Imperium of Terra, and the Quietude's aggressive stance would not be tolerated. The warship and its crew would be returned. Negotiations would begin. Dialogue with Imperial iterators would begin and understanding reached.

The Quietude made its first direct response. It explained, as if to a child, or perhaps to a pet dog or bird that it was trying to train, that it was the true and sole heir of the Terran legacy. As its name suggested, it was resting in an everlasting state of readiness to resume contact with its birthworld. It had waited patiently through the apocalyptic ages of storm and tempest. The Imperials who now approached its borders were pretenders. They were not what they claimed to be. Any fool could see that they were the crude artifice of some alien race trying to mock-up what it thought would pass for human.

The Quietude supported this verdict with copious annotated evidence from its interrogation of the Imperial prisoners. Each prisoner, the Quietude stated, displayed over fifteen thousand points of differential that revealed them to be non-human impostors, as the vivisections clearly demonstrated.

What do you think about this? 🤔