The actual mythology is kind of complicated because it all really depended on who you asked. Many myths tell of Horus as Osiris and Seths brother but in this retelling Horus is Osiris son. I know there are also myths of Horus merging with Ra and become a supreme god after he become king of the living. I think you’re onto something.
IIRC there are two different people named Horus in the mythology: Seth's sibling is "Horus the Elder", but his nephew Horus the Younger is the one most people think about. I think in some myths Horus the Elder somehow disappears and then returns and/or gets somehow reborn as Horus the Younger.
I know this may be weird to say, but I noticed how Horus is a very silent guy-I guess- though not recently due to being close proximity to Seth.
However like before this man had like no presence, things happened around him and like sometimes I forget his even there. He lets his mom do most of the talking, and let's people assume whatever idea of him unless around Seth. I feel he does it on purpose. Like hides it for some unknown reason.
What I'm getting at its that he gives the vibe that he knows more than he lets on, maybe it's just me and I don't remember much of the beginning chapters, but we never actually know any of his thought process.
(Something that hasn't let my mind is that fact in the hieroglyphics Ras and Horus ( and few others but I'm talking about them in specific) are depicted with the same head? Mask? I wonder if that would mean something later on