Now that I think about it, is it really confirmed that all the humans who fell in the Underground before Frisk were children ? Because if I recall, they are represented through their set of weapon/armor :

- Toy Knife with Faded Ribbon
- Tough Glove with Manly Bandanna
- Ballet Shoes with Old Tutu
- Torn Notebook with Cloudy Glasses
- Empty Gun with Cowboy Hat
- Burnt Pan with Stained Apron

The one with the Toy Knife and Ribbon was probably a child, yes, but a gun ? If it's empty, it should have been loaded at some point.

Thanks Doc