How did early humans survive without clothes?

Of course we can survive without clothes. We evolved a hairless body because our ancestor was an ape that was forced to live in the hot, open savanna, where fur is not needed. In fact, many people around the world did not wear any clothes. Native Hawaiians, for example, wore no clothes when the first European explorers arrived. Amazonians and Africans also did not wear clothes. Humans evolved in Africa about 150,000 years ago, and the early humans wore no clothes. Humans started migrating out of Africa about 60,000 to 70,000 years ago. They followed the coast line and went all the way to Australia. These early migrants ended up in places that required no clothes. Only when humans migrated to places like ice age Europe and northern parts of Asia (northern parts of China, Japan and Korea) did they need to wear clothes or animal skins to stay warm. Wearing clothes blocks out the sun and these people were in danger of vitamin D deficiency, which leads to rickets. Rickets can result in muscle cramps, broken or deformed bones and even death. In order to absorb enough UV light to synthesize vitamin D, there was strong selection pressure to evolve lighter skin tones.

The habit of wearing clothes, even in places that do not require them, was spread by European Christians. Basically they forced and/or shamed the natives to wear clothes wherever they went. Of course, not wearing clothes means that humans will no longer be able to live in temperate areas around the world, at least not during the fall and winter months.