the root SUPER reminds us of superman, who is unbeatable
Insuperable has IN, SUPER, ABLE in it. IN means 'not', SUPER means 'over'(root). If you are NOT ABLE to get OVER something, it's insuperable.
if you go IN SUPERmans costume in the fancy dress compition..then u will be ABLE to command respect amongst children as they shall treat you as INSURMOUNTABLE=UNBEATABLE....:D..