So...Nut birthing Ra doesn't relate to the sun arriving upon the horizon at sunrise, after spending 1 whole hour offering its glow from beginning to end before it rises and heralding the end of night as the glow begins?
There seems to be the idea describing the science in some way, even including the glow as being some other 'entity' with another name besides Ra. I do feel that the superstition of things merged into the science of things and better 'myths' were developed to incorporate old beliefs with new.
We certainly accept the lunar/female/matriarch influence as being somewhat more important than the solar/male/patriarch influence in its ways, for all manner of cultures that observed such, and in the case of Menes, he forced solar acceptance into the fore of AE lifestyle and culture which settled which was more important. If one represents a 'god' and is victorious, one's people adopt his own beliefs...that are not just arisen in the knowledge of the people but have been around for quite a long time, and are now front and centre and accepted by the conquered because of how much it is accepted by the conquerors.
As I've said, and as anyone knows when it comes to understanding beliefs, myths and legends, while there can be outright destruction of the old 'gods', it is quite better to incorporate the old with the new in a synthesis that rallies all peoples to the one cause: promoting a whole new way of life. Sam, Joseph Campbell had quite a bit to say about such things, besides others...but I do like his way of presenting the skeletons inside the flesh of human nature.