There is no way for me to know if what the author is saying is true. It's full of assertions and allegations I've never heard before, while also never bringing substantial evidence to back up these claims.
There are bad logical arguments such as: If you have war you cannot have native philosophy/philosophers. There was war in ancient Greece. Therefore, there were no philosophy/philosophers. This implies that any nation that has ever had a philosopher publish something during a time of war, stole that philosophy from somewhere else. This also assumes that the philosophy "stolen" from the "original" place was created in a country that has never had war. If it doesn't assume that, then the "original" country stole that philosophy from somewhere else!
This book essentially dismantles one of the principles of hermeneutics: we can’t hold a modern standard of quality or completeness to an ancient text. It's just not possible. This book also basically ignores the concept that if you put an idea in a box and never expose it to anything, it will never grow. Ideas are sticky. You roll them in other ideas, and your original idea grows, but also takes a more defined shape. We would have no philosophy if we didn't have shared knowledge. Now, is this me defending plagiarism? No, of course not. But we should give authors the benefit of the doubt until substantial proof arises.
Again, my biggest qualm with this book, is that there is no proof, only bad logic and assertions. I truly don't know if the Greeks copied the Egyptians. This book certainly never proved it to me. I'm willing to admit that there should be research on this, but this book is not the end all be all of that research.
I'm in no way suggesting that the Egyptians or other African peoples were not amazing philosophers. It even says in the Bible that the Egyptians were wise (1 Kings 4:30). I'm also not suggesting that the Greeks didn't borrow from them or more. Apparently, according to Egypt and the Exodus by Charles F. Pfeiffer, Plutarch's writings preserved myths of Osiris. There is a lot of nuance to this situation, and I just feel like this book raises more accusations and questions and doesn't give adequate proof or sources to leave the reader with any knowledge that what they read is the truth.