Even if Cronus was humankin, I'm surprised he didn't wear as much jewellery as Eridan since he's [Cronus] the second highest blood in the hemospectrum

Cronus isn’t Humankin, he pretends to be to get attention. He hides his jewelry on a nearby chest to make it seem like the Hemospectrum isn’t a big deal for him to also get more attention, even though he totally sees himself as superior.