Okay, this is yet another one where what’s going on is “obvious” if you are somebody who is steeped in Scripture. But for the rest of us, it isn’t obvious!
Song of Songs is a framing story for a whole bunch of scriptural references to the Lord and Israel. The poet is very skilled, and the framing device is very beautiful, and there are lots of further interpretations about God and the individual believer. It works because it does manage to be a really good love ballad, too.
But it’s about God’s plan of salvation, and His errant beloved people, which later was revealed to include being about Jesus and His Bride the Church.
And yes, it sounded weird to ancient people from the Middle East also. That’s part of how you can tell the references and imagery are being pressed right up to the edge, but it’s also a deliberate way to make the reader or listener wake up and wonder what’s going on. (“Oh, yeah, that’s why the flock of sheep thing!”)
The problem is that you really, really have to look up a ton of references for yourself, or find a really good commentary that is modern enough to just give the bare notes; because most Bibles don’t have all (or any) of the references listed in the little footnotes, and pre-modern commentaries spend a lot of time being devout and drawing out implications instead of giving you the references themselves. (Which is fine, but that means it’s a spiritual experience, not a reference work.)
There was one of the ancient Talmud rabbis who said that all the Scriptures were holy, but the Song of Songs was the Holy of Holies. They didn’t have Jesus yet and the Gospels, so the Song of Songs was the closest thing they had. It’s also very close to messianic material that is also romantic, like Psalm 45 about the king’s marriage.
The first thing that Song of Songs says is “Kiss me with the kisses of your mouth.” Psalm 2 (depending on your translation) says, “Kiss the son.”
Behold, He comes. Behold, the Lord comes.