The King James Bible, the Douay-Rheims Bible, the Webster Bible, and other rigidly translated versions translated the word, shamayim in both Genesis 1:1 and in Genesis 1:5 as "the heaven". However, after the waters were divided and made into the earthy world, the heavenly worlds, and other visible matter bodies, Those lights were called the heavens (plural). In Genesis 1:1 the Hebrew text shows that the definite direct object flag (‘eth) is placed before the noun shamayim (heavens) and (ve’et or, and ‘eth) is placed before the noun ‘erets (earth) to flag or mark shamayim and ‘erets as being ‘joint’ definite direct objects of the verb, bara (created). God's Day-One Creation "the heaven and the earth" is a dual phrase, i.e. it means a "single" group of "two watery identities," more particularly described in verse two as "the waters". On day-one, before the waters were divided, the creation was not a pair, but rather, the heaven and the earth was a dual--a single gaseous-like body of waters--undivided--without form and void (having neither shape nor volume). Likewise, "mayim" (the waters of verse two) is also a very special Hebrew dual (Kee, A study on the dual form of mayim' waters--that very heaven-and-earth pair described as a single entity.
God’s Day-One Creation A type of the Word of God. CircumspectNews.com. from http://circumspectnews.com/?page_id=2364
All things visible were made from those invisible gaseous waters and were each classified as being either, heavenly or earthly bodies--one of the two. That single body of invisible waters is a type of the previously invisible WORD of God that was made visible flesh at a certain point in time under the firmament and named, Jesus, the Christ (Heb. 11:1-3 and Romans 1:20)