Does darker skin color make it easier to live under sun?

Yes it does.

Human skin is composed of three layers: the epidermis, dermis, and fat. Cells in the epidermis (the outermost skin layer) called melanocytes produce melanin the pigment that gives skin and eyes their color. The more melanin is produced, the darker the skin color.

Melanin helps protect the skin against effects of the sun such as skin cancers  and premature aging. In African American skin, melanin provides a sun protection factor (SPF) equivalent to 13.4 compared to 3.4 in white skin and thus the former have lower incidences of skin disorders associated with exposure to the sun.

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.