What was the first language spoken?
The Bible does not tell us. It may have been Hebrew, but we do not know. When God confounded the languages at the Tower of Babel, one may assume that one language did not change there, and that was the godly line.
Genesis 11:4-9 says, “And they said, Go to, let us build us a city and a tower, whose top may reach unto heaven; and let us make us a name, lest we be scattered abroad upon the face of the whole earth. And the LORD came down to see the city and the tower, which the children of men builded. And the LORD said, Behold, the people is one, and they have all one language; and this they begin to do: and now nothing will be restrained from them, which they have imagined to do. Go to, let us go down, and there confound their language, that they may not understand one another’s speech. So the LORD scattered them abroad from thence upon the face of all the earth: and they left off to build the city. Therefore is the name of it called Babel; because the LORD did there confound the language of all the earth: and from thence did the LORD scatter them abroad upon the face of all the earth.”
The Bible does tell us that God will one day restore the world to one language again. Zephaniah 3:8,9 says, “Therefore wait ye upon me, saith the LORD, until the day that I rise up to the prey: for my determination is to gather the nations, that I may assemble the kingdoms, to pour upon them mine indignation, even all my fierce anger: for all the earth shall be devoured with the fire of my jealousy. For THEN WILL I TURN TO THE PEOPLE A PURE LANGUAGE, that they may all call upon the name of the LORD, to serve him with one consent.” Until that day, the languages will remain varied.