Could it have been possible that Goliath was one of the Nephilim that had been reborn after the flood?
The Nephilim first appear before the flood in Genesis 6:1-4. Many scholars believe they are the offspring of the sons of God, or angels, marrying the daughters of men. It’s believed that the Nephilim best fit the description of giants.
Strangely enough, after everything is destroyed in the flood, we find the Nephilim referenced once again (Numbers 13:33). This happens when the twelve spies go into the land of Canaan to see what they’re up against. Moses permitted them to go in after the people suggested it.
As the spies report what they have found, they mention these Nephilim they saw in the land. A parenthetical statement connects the Nephilim with the sons of Anak. We know this refers to giants. This may confirm that Nephilim also refers to giants when it is used in the Hebrew Old Testament.
There is a clear relationship between the Nephilim and the Anakim. However, it appears to be lingual rather than literal. Anakim were giants in the land of Canaan, probably going back to the Philistines. But the Israelite spies refer to them as Nephilim, connecting the Nephilim with giants. Goliath was certainly a giant, about nine and a half feet tall.
Using Nephilim for giants was the equivalent of using Coke to refer to all soft drinks. Coke is a name brand of a soft drink, but many people in the South use it to refer to any soda.
So it becomes a linguistic connection rather than a literal one. So the Nephilim did not survive the flood. But the name “Nephilim” became the word the Israelites used to describe any giants they saw.