Actual thought I had in the shower!
Gelatin was originally and still often is derived from meat by-products, so wouldn’t it make more sense as a meat dish?
I looked it up, and it turns out that accounts of aspic (a savory gelatin dish) predate the earliest record of gelatin desserts by more than half a millennium!
Maybe the mid-20th-century meat Jell-O trend makes more sense than I thought
You are right, however aspic tastes terrible and is used more for presentation in traditional Garde manger
I think it was more of a marketing switch to make it sweet cause well its easy to add suger to stuff and then it tastes good. Sugar and salt can mask the flavors of ultraprocessed foods, especially the kind that that leach out of the metal in a factory production line.
There are plenty of foods that hat are sweet buy have animal source origins. Take for example the Oreo cookie filling which at first was equal parts pork lard and sugar. Also, anything with dairy and eggs so cake and ice cream also fit into this.