The only way someone can sow the seed of doubt that Kemet (Egypt) was built by anyone other than Africans, is by creating a divide between it (Kemet) and the rest of Africa. They have to make Kemet appear uniquely unlike any other African nations. This, of course, is accomplished primarily by way of not highlighting any other African nations that bear any similarity to Kemet or any that may have coexisted with it.
Once you begin to reconnect the legacy, customs and culture of Kemet to its fellow African nations, it will make it very hard for foreigners to claim the credit for its creation.
There is one thing everyone should always remember and never leave out of the conversation when talking about the ancient Kemetic people. That is, these people, the Kemetians/Egyptians are not originally from that landmass known as Egypt today. They are from somewhere else, in the deeper parts of Africa, where they claimed is their original homeland.
The next very important part of this equation to also pay attention to is this. If you go into the land where the Kemetians said they are from, you will see, explicitly, the same types of buildings, culture, customs, language, etc. as that which is found in Kemet/Egypt. While outsiders are claiming ownership of ancient Kemet, most of them are completely unaware that this culture existed first in other parts of Africa where their ancestors have never been to.
The Kemetic people said that they are from Nubia, which by far, predates the very existence of Kemet/Egypt. Nubia, which is modern day Sudan, is the parent country of Kemet. The land called Egypt today is only a land that they, the Nubians, migrated to build what the world know today as ancient Egypt. In fact, there are much more pyramids in Sudan than there is in Kemet.
It is also important to always note that Kemet was not only the baby of Nubia; it was a part of a series of similar African nations, which are known today as the Nile valley civilizations.