Why did God do something totally different after the Tower of Babel?
Because false religions, pagan religions, and idolatry arose at the Tower of Babel, God did something totally different. He allowed the human race descending from Adam to flow like a river, then called one man, Abraham, and from him brought forth the nation of Israel, the Jew.
Les explains that the 200 years after the Flood led to the Tower of Babel, where the nations appeared and God separated them by confusing languages. After another 200 years, the false religions, pagan religions, and idolatry that came in at Babel caused God to do something totally different. He let the human race coming from Adam flow like a river, and out of that river of humanity, with the call of one man, Abraham, came the appearance of the nation of Israel, the Jew.