Well, God works in nature, and also above it; He uses nature to sustain the universe, but that does not mean that He is bound by the laws that He has set in place. For example, ordinarily, God feeds His creation through food from nature. However, at times He also feeds supernaturally, like when Jesus fed great crowds of people using only a few pieces of bread and a few fish (Matthew 14:13-21, Matthew 15:32-39), or as He feeds us with His body and blood in the Holy Eucharist (1 Corinthians 10:16). He's not constrained by natural law, but He is free to break it (Luke 8:25), and the reason He breaks it is to show us something important — namely, Jesus Christ. So, instead of doubting that something occurred, it's more profitable to consider what the amazing miracles mean for us!
Both the Old Testament and the New Testament are packed with miracles. These miracles do not occur naturally — if they did, they wouldn't really be miracles — rather, they are exceptional works of God recorded for us in history. The Apostle John through the Holy Spirit tells us exactly why these miracles occurred — that they were not fundamentally for the benefit of those to whom it happened, but for us. He writes (John 20): "Now Jesus did many other signs in the presence of the disciples, which are not written in this book; but these [miracles] are written so that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name."
However, I noticed you included the long age of Methuselah, and that is a bit different. Originally, when God created the human race, He did not intend for us to die. Death is a consequence of sin. In the age after the fall, however, humans slowly deteriorated, and originally, they were blessed with long lives. But we learn in Genesis 6 that God limits the lifespan of mankind to 120 years. This is a consequence of our continued rebellion towards God. But in either case, a long life, life itself, miracles, and all good things, are gifts from God.