"Casserole was always something made with concentrated soup mixed with leftovers and rice growing up."
Wikipedia calls that the 'American casserole' variation, which became popular post WW II and which also eventually made people kind of anti-casserole because of the high sodium, high fat, and the general turn against "convenience foods."
The traditional definition of a casserole is generally a combined dish made with several main ingredients and a liquid (often serving as a binder) and cooked in a casserole dish.
Lasagna, baked ziti, shepherd's or cottage pie, pot pie, cassoulet, mac and cheese, all are casseroles.
All that said, I didn't bake the ham yesterday... I cooked it in the crock pot on high for about 5 hours. I had my doubts about it, but I found a bunch of stuff on line saying it was a good way of doing it. And it was. Turned out fantastic. The meat was firm, tender, juicy, and not at all dried out. And it seems as if its trip through the crock pot concentrated the ham flavor more so than baking it.
And now I have a bunch of ham left over and a very nice, meaty bone with some broth that I'll turn into soup.
I think this weekend the first thing I try is going to be the mushroom tagliatelle with ham.
After that, I'll have to figure it out.