As a kid growing up in the US, I learned to distinguish jelly/jam/preserves this way.

They are all sweet and fruit-based, and used to spread on toast at breakfast, or on peanut-butter sandwiches as a snack for kids.

Jelly is clear, or nearly so, because as much pulp and fiber as possible has been strained out of it by pouring the liquid through a cloth before it sets. It wiggles when you shake it, and you can see through it.

Jam has some of the pulp left in (I suppose because it is strained through a coarser cloth or maybe a colander?). It doesn't wiggle, and you can't see through it. It has more of a pasty texture, but is uniform, with no lumps.

Preserves are lumpy because they have visible, recognizable chunks of cut-up fruit in them.

I know drippings from meat if left to cool, would sometimes form gelatinous goo in the bottom of the pan, but we never ate it in that form. (Instead, my mother would usually add flour to the drippings it and cook it into gravy.) I didn't know any name for that gelatinous stuff. It would never have occurred to me to call it jelly because, in my opinion, it was disgusting and inedible, especially since it was brown instead of fruit-colored. I remember seeing similar stuff in a canned ham.

I never heard of aspic and probably would have refused to eat it if I had seen it.

Jell-O was just Jell-O. I seem to recall that at some point it was advertised as "Jell-O brand gelatin dessert," probably because the maker did NOT want their brand name to turn into a generic term, because then they would lose the exclusive right to use it. (Such is the price of having a near-monopoly.) Anyway, that's how I learned the term "gelatin."

In my limited experience as a child, NO form of gelatin was ever served with meat—cranberry "sauce" being the unique exception; it was served with turkey at Thanksgiving. But it was called "sauce," not jelly or gelatin, although it had all the characteristics of jelly.