From the moment that Made in Abyss introduces Riko, it shows her as a headstrong, ebullient, and curious young girl. Her initial conversation with fellow red whistle, Nat, establishes their dynamic — Riko, the curious one who hordes valuable relics and thinks too far ahead of where she’s at, Nat, the one who cares about her but hides it under a layer of bluster.
The problem Riko runs into while excavating isn’t that she’s incapable of finding things but that she finds so many relics, it’s difficult for her to carry them all in her backpack. She acts instantly when Nat is in trouble, getting herself in trouble in the process.
No sooner has she been rescued by a strange light than Riko stumbles upon a prone body. When she prepares to resuscitate him, Riko discovers that not only is he not breathing, he’s also not human. Rather than reacting surprised, scared, or shocked, she’s enchanted. Riko immediately begins poking and prodding him, taking in a more detailed snapshot of his appearance, once she realizes that he’s not dead. Then, naturally, she hauls him behind her as well, another relic for her collection.