Languages evolve over time. The modern English we speak today is vastly different from the old English of a thousand years ago, and a thousand years before that people were speaking classical Latin. Ancient Egypt existed for nearly 3000 years, so their language must have evolved in that time. How did hieroglyphs change over time? Or did they stay relatively consistent?
Great question! Yes, the Egyptian language and writing systems changed quite a lot over time. I wrote about this in How much did hieroglyphics change over time?