Is Hebrew the oldest language? And did Adam and Eve speak Hebrew?
The answer to both questions is probably “No,” but no one can know for sure. Remember that in the beginning everyone spoke the same language (Genesis 11:1), but God made different languages at the Tower of Babel. In Genesis 11:7, God said, “Come, let us go down and confuse their language so they will not understand each other.”
When God confused the original language (which was the oldest language and the one Adam and Eve would have spoken), then the first language might have been lost. Hebrew probably was created after the confusion at the Tower of Babel. We really cannot know for sure what Adam and Eve spoke, but we do know that through the wonderful gift of language, God allows us to communicate His will to people all over the world.