Exodus 7:20 And Moses and Aaron did so, just as the Lord commanded. So he lifted up the rod and struck the waters that were in the river, in the sight of Pharaoh and in the sight of his servants. And all the waters that were in the river were turned to blood.
Each plague attacks an Egyptian god. The first attacks the life of Egypt – the River Nile.
People can live without many things but water is not one of them. Life is not possible without water.
The waters of the Nile turn to blood. It kills the fish, which cannot escape the water, and runs off those animals that can escape. However, if those animals leaving the water cannot find water, they die also.
The first plague of blood begins this period of death.
Contrast this with the Israelites using blood during the last plague to give life.
Many years before God told Noah, “You shall not eat flesh with its life, that is, its blood.” Gen 9:4
Indeed, life is in water and life is in blood.
Pharaoh ignored the plague and, therefore, brought death upon his land through the following plagues.
Pharaoh ignored the blood because his magicians were able to counterfeit the same thing.
And this is the key!
When you ignore the Blood [of Christ] you bring death.
When someone you trust tells you the Blood [of Christ] is not the way or there is a better way you bring death.
When Jesus died He wiped away this plague of death – John 19:34 But one of the soldiers pierced His side with a spear, and immediately blood and water came out.
John also says: This is He who came by water and blood — Jesus Christ; not only by water, but by water and blood. And it is the Spirit who bears witness, because the Spirit is truth. For there are three that bear witness in heaven: the Father, the Word, and the Holy Spirit; and these three are one. And there are three that bear witness on earth: the Spirit, the water, and the blood; and these three agree as one. 1 John 5:6-8
Do not let the adversary deceive you with claims of easier ways to salvation. It does not happen but by the Blood of Jesus.