Yeah, I believe "figures" is a non-specific catch-all for pretty much all types of units with health.
"Figure" is a defined game term that refers to any "hero" or "monster" in the game. LTs are considered "monsters" and therefore inherit the status of "figure" despite not actually being a plastic figurine. Some NPCs and familiars are called out explicitly as being "treated like a hero figure," but that's on a case-by-case basis.
It's probably true that most "units" which have a health rating are also "treated as figures" if they aren't actually figures by virtue of having a plastic figure to represent them, however, there may be some exceptions. By default, any figure represented by a cardboard token is NOT a figure, unless the rules say otherwise.
Maybe it wouldn't work for, say, the Geomancer's summoned stones, but other than that I think everything but the giant/troll himself gets caught up in the sweep.
Yeah, I'm pretty sure the summoned stones specifically say "monster" instead of "figure."