SecularFrummy,
That isn’t quite accurate. “Eretz” is certainly used in Tanach to mean more than just land. It is used to refer to the whole realm wherein man functions. WIY cited one possuk, and there are many that refer to “Eretz” in contrast to “Shemayim.” Shemayim itself is sometimes used to refer to the sky and sometimes to refer to greater space and sometimes to the metaphysical realm inhabited by angels and the like.