… that it’s very possible that David did not slay Goliath.
Yup. Its right there in Samuel II. There are two very clear, very contradictory accounts of the way that Goliath is killed. In 1 Samuel 17, you can read the familiar story of David vs Goliath.
But! Then you read on and get to 2 Samuel 21 there is an account that is part of a four chapter random insertion into the otherwise chronological story of David. And these four chapters are older than the rest of the Samuel books. They were probably written during David’s lifetime. Making them possibly more accurate than 1 Samuel 17. And in it they clearly state a list of giants who were slain at the hands of brave Israelites. And Goliath is one of those giants. And in this account, his slayer is some fella named Elhanan. The King James version puts in ‘the brother of’ Goliath to make this whole thing make sense, but the Hebrew original says nothing of a brother. It clearly states that its just plain ole Goliath.
That ought to give you something to chew on for a while.