GE 10:5, 20, 31 There were many languages before the Tower of Babel.
GE 11:1 There was only one language before the Tower of Babel.

Why should this be viewed as inconsistent?  There is no inconsistency.

The verses in Genesis chapter ten speak of the division of the people that occurred in chapter eleven and the resulting nations and languages which came from that division.

The statements in chapter ten are not chronologically before the division of the nations in chapter eleven.  They are descriptive of the division that occurred in chapter eleven.