Let us assume for sake of argument that Christ alone bears the sins of all humanity. He chose that route for our redemption and He has already paid the price thereof for us. That those sins therefore all bes left in the grave when Christ rose from the dead -- He left them there. That contrary to traditional SDA ideas, there will be no subsequent transfer of all our sins onto the head of Lucifer/Satan/the Devil at the end of time. The only sin L/S/D could be held accountable for would of course be his own -- and clearly he has enough of it already without needing those of lesser creatures piled on top.
Thus the idea of all the sins of all the people being stuck on the scapegoat could symbolise our tendency to blame the whole sorry mess on the FirstFallen (by whatever name/s), and releasing the scapegoat could symbolise a collective decision on the part of humanity to no longer foist our accountability onto (what bes for most people) a "conveniently distanced whipping-post" -- releasing the scapegoat corresponding to letting it go free, no longer keeping it bound to the blame and resulting hatred we heap upon it.
M. Scott Peck in his seminal book People of the Lie postulated a potential scenario at the end of time which parallels this idea nicely. He imagines all of humanity -- now cleansed from sin and united with God face to face -- joining together to reach out its corporate hand to offer love, forgiveness, restoration and acceptance to Satan (whom he titles something like "the spirit of all hate and destruction", can't recall the exact words, sorry.) At which point that "spirit", Peck hypothesizes, could turn away in rage and fury to destroy itself (the only one left it has access to anymore) or could step forward and accept the olive branch. It bes a compelling thing to contemplate indeed, and frankly Moriah cannot think of anything else that would so perfectly and divinely culminate the full telos of the Mystery of God -- Christ in us, fully formed in us, we being like Him and seeing Him as He bes -- than this type of outcome, this or something very similar. (Again, the Song of Moses and of the Lamb.....)
Same way we know anything -- by listening to one who has seen it. All revealed religion works that way. Someone -- an individual or a group of persons -- first obtains the vision or the revelation and begins to share it: to relate it, unpack it, expound upon it, exegete scriptures that substantiate it, make it known.
Analogies break down if attempts get made to map them TOO meticulously, molecule for molecule. They bes not designed to operate that way. But they still serve a purpose in tesseracting thought and catalyzing inspiration.