Everyone on earth had the same language and the same words.
...One language - that is what caused the first sin. This is that they agreed to stop in one single place. And this is against the will of God that said to "fill the land and replenish it" - that is, to walk to all its places, since the land was created to be settled.
...And the same words - The text did not explain what those words were, rather, it leaves as a hint, as explained in midrashim. But the words themselves are not explained by the text, it just tells us that they were the same words, to teach us that it wasn't because of the content of the words themselves that the Holy One of Blessing was distressed. They were what they were, and in its simplicity there is not sin, and on the contrary all appears well. But here what happened is that all thought the same thing, and this came to be the problem of the settlement.
Burn them thoroughly - There is no place in the Text where something is told that has no impact in the story [therefore, ask:] Why do I care if they were using stones; bricks; were constructing using wood; or made their brick by burning? Even before the Flood it is written "and afterward he build a city" (Genesis 4:17)! And it appears that here there is a hint regarding our sages' tradition that Avraham Avinu was thrown in the fiery furnace - and from the verse "that took you out from Ur Kasdim" (Genesis 15:7) there is no real proof, since from the simple meaning it is simply the name of a place, as it is written "in the land of his birth, Ur Kasdim" (Gen. 11:28) "and went out with them from Ur Kasdim" (Gen. 11:31) etc. But from here we have a hint to the issue of what obviously was happening before the tradition saying that they threw Avraham Avinu into the fiery furnace: they did not make the furnace for this need [to burn people], rather this was the fiery furnace (in Daniel, see Dan. 3:6) done for the need of people [to fire bricks]. And the Text is informing that this furnace was for the need of the city and the tower, and from this we understand how big and deep was this furnace, and from this furnace Avraham Avinu was saved.
Burn them thoroughly - There is no place in the Text where something is told that has no impact in the story [therefore, ask:] Why do I care if they were using stones; bricks; were constructing using wood; or made their brick by burning? Even before the Flood it is written "and afterward he build a city" (Genesis 4:17)! And it appears that here there is a hint regarding our sages' tradition that Avraham Avinu was thrown in the fiery furnace - and from the verse "that took you out from Ur Kasdim" (Genesis 15:7) there is no real proof, since from the simple meaning it is simply the name of a place, as it is written "in the land of his birth, Ur Kasdim" (Gen. 11:28) "and went out with them from Ur Kasdim" (Gen. 11:31) etc. But from here we have a hint to the issue of what obviously was happening before the tradition saying that they threw Avraham Avinu into the fiery furnace: they did not make the furnace for this need [to burn people], rather this was the fiery furnace (in Daniel, see Dan. 3:6) done for the need of people [to fire bricks]. And the Text is informing that this furnace was for the need of the city and the tower, and from this we understand how big and deep was this furnace, and from this furnace Avraham Avinu was saved.