If you look for the root word, nefal, or its root palal, you will get enough to run around in circles for many weeks. nephalim=Strongs 5303, nephal=5307, palal=6419. These words justify the statements I made originally, which are extracted from the Jewish commentaries which tell an expanded story. The commentaries are not Scripture, but they can be made to answer for the "gods" from before the flood found n Egypt, Sumeria, China, etc.
If you do not go that direction, you have only the two verses. Read them in Hebrew, and you will get a different story from what is commonly taught, but does not contradict what I am saying. The nephilim created the giants, and some giants survived the flood, or were recreated after the flood by other nephilim.