and the time to think this through. If you look at the human body, how is it adapted to survive without tools and clothing? Its much like looking at an antique or ancient tool and wondering how was this used? The fact is a naked human would not last more than a few days on a hot savanna, limited food, water and wall to wall predators. With a shore line existence, it's a different story. Plenty of water, diving ability that gave access to shell fish with omega 3 acids, helping brain growth, and the ability to dodge land predators by swimming out beyond their reach. Most land predators will not follow their prey into the water beyond their ability to walk. Once a predator starts to swim, its helpless, much like a dog chasing a raccoon into the water. The raccoon will swim right up on the dogs back and either blind it or force it to drown.
Plus where do you see humans (partially) unclothed now? At a warm water beach, most land mammals don't like to swim, people instinctively do.
I posted a BBC documentary below that went into more on this, check it out, I thought it was interesting.