How would the north American colonies have been different without slavery?

The people living in the colonies were just barely surviving in the living conditions there. They would definitely not be able to stay alive and do the necessary labor the needed/wanted. Most of the Native Americans were dead and the main reason was the weak immune system. Africans had developed a resistance to malaria and other common sicknesses to the English. Also there was a bunch of them so replacements would come easy.