Elhanan, son of Jair
Elhanan son of Jair-Oregim the Bethlehemite ( "’Elḥānān ben-Ya‘rê ’Ōrəḡîm Bêṯhallaḥmî") appears in 2 Samuel 21:19, where he is credited with killing Goliath. As this contradicts the better-known story in 1 Samuel 17 in which it is the famous David who kills Goliath, the 4th century BC Book of Chronicles explains the second Goliath by saying (20:5) that Elhanan "slew Lahmi the brother of Goliath", possibly constructing the name Lahmi from the last portion of the word "Bethlehemite" (""beit-ha’lahmi"). The King James Bible translators modified 2 Samuel 21:18–19 to make it read as if Elhanan had slain Goliath's brother: "And there was again a battle in Gob with the Philistines, where Elhanan the son of Jaare–oregim, a Beth–lehemite, slew "the brother of" Goliath the Gittite, the staff of whose spear was like a weaver's beam", although the Hebrew text at this point makes no mention of the word "brother"; the medieval Jewish authors of the Targum Jonathan solved the problem by explaining Elhanan as an alternative name for David. However, this makes it difficult to explain why David is called "Elhanan" in verse 19 but consistently "David" in the verses that surround it (15, 16, 17, 21, 22). The most widely accepted explanation is that the storytellers have displaced the deed from the obscure Elhanan to the more famous character, David.
The Samuel Scroll
With the discovery of the Dead Sea Scrolls in which the manuscript containing 1 Samuel 17:4 is found in original Hebrew and can be dated to over 1000 years before the Masoretic Text, the height of Goliath as four cubits and one span is not only a confirmation of the readings in the original Septuagint and in Josephus, but is also a far more reasonable height for a man and not a medical impossibility. As time went on, the ancient narratives became more exaggerated as the passage was copied and recopied many times. Even in later Septuagint manuscripts, Goliath’s height is recorded as "five cubits" and in an even later manuscript as "six cubits", exemplifying how ancient narratives were sometimes exaggerated as they were retold and rewritten by narrators or scribes. Perhaps the story of a young and unarmored David defeating a mighty Philistine warrior would have seemed all the more miraculous the taller Goliath was, contributing to an even more heroic image of David as a leader later on in life as he put his faith in God and defeated countless adversaries. With David being a key character in the narrative of Scripture, such exaggeration in the telling of this story is understandable.