I think everyone's digging to deep.
Continuing on what numerous people have said, Horus stands for good and Seteh stands for evil, but, in my opinion, they're just saying that humans have both good and evil in them.
When it says, "Thou art born for Horus dwells in thee," then "Thou art born for Seteh dwells in thee," I personally see it meaning, basically, that, yes, you are human because you are good and evil.
The rest is probably just a dictation of what the journey to the afterlife is like. Notice how they brought up a Unicorn? Because Unicorns are widely believed extinct/fictional, perhaps that represents the Pharaoh's arrival in the place of dead things for, even if the Unicorn was never real, it is still a fantasy that died somewhere along the line.
This is my interpretation, I mean no offense by it.
I think everyone's digging to deep. Continuing on what numerous people have said, Horus stands for good and Seteh stands for evil, but, in my opinion, they're just saying that humans have both good and evil in them. When it says, "Thou art born for Horus dwells in thee," then "Thou art born for Seteh dwells in thee," I personally see it meaning, basically, that, yes, you are human because you are good and evil. The rest is probably just a dictation of what the journey to the afterlife is like. Notice how they brought up a Unicorn? Because Unicorns are widely believed extinct/fictional, perhaps that represents the Pharaoh's arrival in the place of dead things for, even if the Unicorn was never real, it is still a fantasy that died somewhere along the line. This is my interpretation, I mean no offense by it.