A lot of logic for Character visuals, such as clothing, is bound to the Humanoid instance. That has the unfortunate consequence that a removed Humanoid results in clothing no longer being rendered.
You could bake clothing textures onto the character meshes directly, use Package meshes (that already have some clothing built-in), or chop up your clothing textures and paste them onto every body part with Decals. Decals would project the image onto the mesh, effectively giving the same result as baking the texture yourself.