I think the most telling SE moment is not an SE moment at all, in that it was in the original but it foreshadowed what would eventually come along some 14 (?) years later.
In ROTJ, there’s that exterior shot of Jabba’s palace, where a frog-thing eats an insect-thing…and then burps.
For years I thought that was an SE addition, until I watched Harmy’s Despecialized Edition and found out it was in the original.
Funny I thought the same thing too. I always thought the same thing too. It always had an almost digital look to it. Perhaps its because its far away.