The Egyptian gods were associated with concepts such as death, sun, etc... which may explain why there were "so many"!
There are many Egyptian gods and goddesses, so many that no official list of names exist yet.
Set was a god, not a Egyptian.
There are so many reasons
Everything's been defeated by the Egyptian Gods, so yes. It has.
Aton was different because he was the god of monotheistic gods when Egyptian belief was all about many gods and monotheism is one god
Over 1,500 names of Egyptian gods and goddesses have been recorded.
Narmer was a ancient Egyptian king, so a priest and warrior of the gods and goddesses he worshiped.
Horus is a Egyptian god, there are many gods identified with him.
1
Is is not a firm count of Egyptian gods and goddesses confirmed.
Creation myths
There is no official list of gods and goddesses of ancinet Egypt, but the links below will help to find out more.