Final answer:
The layer of the epidermis that has simple cuboidal cells responsible for skin regeneration by producing squamous epithelium is the stratum basale.
Step-by-step explanation:
The layer of the epidermis composed of simple cuboidal cells that act as a germ layer, producing layers of squamous epithelium above, is the stratum basale. The stratum basale, also known as the basal layer, contains basal cells which are a type of stem cell that divides to form all the keratinocytes of the epidermis. These keratinocytes originate as cube-shaped cells with little keratin and as they divide, the newly formed cells are pushed upward, gradually flattening and accumulating more keratin to become part of the squamous epithelium. This process is essential for the regeneration of the skin's surface, making the stratum basale a crucial component of the skin's renewal system.