From the same root as nautical, 'natant' just means swimming, floating. Supernatant is above the water. Supernatant refers to one type of liquid that does not mix with another and so stays on top. Like oil and water.
Oil in the Bible is synonymous with the blessing of God, His anointing. Jesus refers to the Good Samaritan (in Luke 10:34) "pouring in oil and wine" as he cares for the wounded traveler.
Oil also symbolizes the Holy Spirit. The five wise virgins awaiting the bridegroom in Matthew 25 (verse 4) "took oil in their vessels with their lamps." The point here is that the oil of God, be it for light or for healing or for anointing and blessing, is so radically different and precious as to not even be compared with that which we can muster alone.
Oil symbolizes unity and brotherly love: "Behold, how good and how pleasant it is for brethren to dwell together in unity! It is like the precious ointment (essentially olive oil) upon the head, that ran down upon the beard, even Aaron's beard: that went down to the skirts of his garments;" (Psalm 133:1-2) Here, just like the prior examples, oil (ointment) is seen as the blessing of calm and peace in interpersonal relationships. Something from above. "He that soweth discord among brethren" is listed among the six things the Lord hates in Proverbs, chapter six. When you and your friend's gears grind for lack of oil, know that God has all you need and will help you through via the Holy Spirit. One of the great tragedies of life is a relationship that spoils because one or both refused to "pour in oil" to dress and address a wound brought about by negilgence and ill-humor. God knows. He'll keep things flowing smoothly. Ask for the oil of the Holy Spirit to do its (His) thing. He won't let you down.
Now, "oil and water don't mix". You'll hear that in school and find it to be true in life. When you mix up french dressing, voila! Without any vinegar, the two won't stay together. Vinegar acts as the emulsifier between the two. Vinegar, which is essentially fermented wine (which in turn is fermented grape juice), enables the two to mix. That's good news because vinegar is what you get when you suffer. The wine of life sits and sits and ferments. You think nothing's happening, but God is working all the disparate ingredients into something unique, something beautiful. The pieces will come together and it will all make sense. In His time.
It's interesting to think about baby Moses who, in Exodus chapter 2, is hid in a basket by his mother and sent to float down the Nile in order to escape the genocide of male babies in Egypt. Floating, natant. Contrast that with Jesus, who in Matthew's Gospel (14:25), "went unto them (the disciples), walking on the sea."
Can't get more supernatant than that.