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
It’s flavorless once you’ve extracted it, but how easy is it to get it pure enough that it doesn’t retain meaty flavors? (I genuinely don’t know, I’ve never done it myself)
I don’t think you can get pure gelatin from animal sources without losing the meat flavour. Gelatin from animal sources is made by a process involving hydrolyzation, which breaks down the muscle proteins into pepides. The proteins in meat are the main reason for its identifiable flavour. The broken down peptides in gelatin don’t taste like anything. If the gelatin still tasted like meat it would indicate that the gelatin extraction process was incomplete.
Even if it was possible to do some kind of half-assed gelatin extraction process that preserved some of the animal flavour, there’s no market for that. People who buy gelatin expect it to be flavourless, so they can use it in their recipes without the gelatin affecting the taste. Gelatin is used to provide a thick and, well, gelatinous texture. If someone’s making a recipe involving gelatin that’s supposed to taste meaty, they’re gonna use their own animal products (i.e. meat and/or meat-based stock).