Just thought of another reason. Based on the story line from the movie, the goa'uld were "kicked out" of Egypt before the rise of Christianity and other major religions. Since the goa'uld live "a long time" and would have been established as Egyptian gods, this would not necessarily fail where other episodes show humans of later periods (such as "Demons") but does get a bit weak there. Then again, so does the presence of those humans on the other planets (unless they were taken in ha'taks but there should have been some reference in Jackson's research to the UFOs).
Just a thought. I'll admit there are a couple holes there tho.
Just a thought. I'll admit there are a couple holes there tho.