It signifies "over" whenever "over" is used in the sense of "beyond".
"Somewhere over the rainbow" does not mean "somewhere located vertically above the rainbow" (supre); rather, it means "somewhere on the far side of the rainbow" (preter).
Actually, in my comment, when I typed "supre" I was thinking "super". I can't recall coming across supre in DuoLingo yet. (And, if I did, I am sure I confused it with super. Kind of like theater versus theatre or meter versus metre.)
- Super is a preposition and supre is an adverb.
- Both mean "above", while supre can also mean "upstairs".
- The examples sentences don't seem to support a difference between the two related to touching. For example:
La luno kaj la steloj brilis super ni. The moon and stars were shining above us.
La steloj briletas supre. The stars are glittering above.
I'm also from the Sunflower State and am also often besieged by Wizard of Oz references. Sometimes I wanna tell people what they can do with their ruby slippers. Instead I just remind them that In Cold Blood was also set in Kansas.