Different people have different skin, oils, water supplies and diets.

Everyone needs to clean themselves regularly, but the exact details of what that means varies by circumstances.

Most people are fine with shampoo, a gentle soap, and warm water.
As long as you're getting rid of old dead skin, excess oils and any grime you're fine though. Soaps make that easier, but they're not a requirement.
I'm prone to dry skin and greasy hair, so I use a shampoo, cool water and a scrub brush instead of soap for my body. Perfectly clean, just need to scrub a little longer to make sure I get everything.