Why do humans have skin not fur?

It appears humans lived in the sea because the only raw meat we can eat is seafood. That's why our only fur is on the top of our head. Also fire hasn't always existed so we couldn't have lived off raw game like monkeys and apes. In other Words they aren't our ancestors

It is claimed elephants' ancestors are whales. Since we have the same amount of fur wouldn't we have also originated in the sea.