[(E)]

Semi-disposable cork but plates, leather you have mentioned but maybe laminated or stuffed with horse hair or wool. Another possibility would be complex basket weaves of hemp/sisal/linen rope. Oilskin or oiled canvas with padding.

A more complex leaf spring maybe, torsion and compression springs for that matter.

Alternatively padding could be part of a soldier/sailor/marine's uniform.

Horn might work but it may be too susceptible to water damage

Just ideas anyway