jsprog is most likely correct you appear to have extruded all the faces.

But that is not what you described. It sounded to me from your desription that every time you create an object you were getting multiple faces.

There are two ways to extrude faces, one by selecting all the faces then using the edit mesh / extrude or the marking menu version. Two selecting the entire object and pressing edit mesh / extrude (this is most likely what you inadvertently did).

You can fix this though using mesh / cleanup and selecting delete laminar faces. This should delete all the faces that are occupying the same space.

Good luck.