Well when you think about it, is possible that none of the other humans made it to Asgore. Every set of equipment that the last fallen humans used were all found before the throne room, when you look at it that way they may have all met their fate around where you find the sets.

The one with the faded ribbon and the toy knife could have been found and killed before Toriel moved to the ruins.

Tough gloves and bandanna died in snowdin.

Tutu and ballet shoes at water fall, along with worn notebook and cloudy glasses.

apron and pan was stopped at hotland.

And empty gun with cowboy hat made it all the way to the core.

Papyrus does kinda say he wants them captured…

And asgore doesnt want to kill them, so any chance they get to live he will probably take.