Would a child grown in total isolation develop a language?

It depends on the surroundings. “How isolated” is the real question. Human children learn by imitating and identifying the reactions to these communications. Like, when we say food and use hand gestures, kids confirms the action and result. They then try to do the same next time and expect the same result. If we leave them in isolation i.e. no human contact (even of their parents) then they will learn from the environment. If they are resilient to survive they will learn from interactions with plants, animals and other humans.