If a person is unwilling to believe this verse, they will be unable to believe anything that follows.
Our Lord is Creator of all things and the upholder of all things by the Word of His Power. Heb 1:3
Genesis is revelation knowledge of the origin of all things. All other explanations are foolishness based on man`s rational mind and its limitations.
Though life spans greatly reduced after The Flood, we also have Abraham being the patriarch of what would be later called the Children Of Israel - Israel being his grandson. The Children of Israel dwelt in Goshen for 400 years when Moses was born.
Moses penned the creation account which had been passed down from generation to generation by a people to whom heritage was important. I am confident that the details of the creation were filled in when Moses spoke with our Creator.
It explains why science is unable to fathom the essence of matter. They have reached the point where the energy to inspect the smaller particles moves them (Heisenberg uncertainty principle). If they were able to keep delving they would find nothing material, only Jesus` spoken Word!
The Holy Spirit is The Majesty. Jesus is His physical form. The Majesty is not defined by dimensions. He is infinite. Jesus` body is finite but He is the focal point of The Majesty. We cannot `see` His Holy Spirit in the same way we `see` Jesus. - Joh 3:8
So we see that it is the Word Of The Lord that causes all things to exist and makes the laws by which it operates.
Science will never get into the mind of God though it may come to a clearer understanding of this Creation Essence truth.
How His Word can do these things is amazing!