Ancient Egyptian language and society changed more over the millennia than is commonly supposed. In any case, one should keep in mind that monumental hieroglyphic inscriptions were always a rather small subset of texts in ancient Egypt; the vast majority of texts were written on perishable materials in hieratic or Demotic, and these abbreviated writing systems certainly changed quite a bit over time.

There's always more to be said on the topic, but I've written about this in a few past posts.

• How much did hieroglyphics change over time?

• How is the Old Egyptian Language different to Middle Egyptian?

• Ancient Egypt is often described as the longest continuous human civilization, and seems to have maintained a surprising amount of cultural continuity. How accurate is this description? If so why were they able to maintain continuity so much more than other civilizations?

Note especially my discussion of the notoriously complex Ptolemaic temple texts in the third thread.