Judaism grants a special status to the firstborn male child. In every home, the birth of the first child is a special occasion preceded by preparations and a sense of excitement. The parents’ attitude toward the newborn is usually one of awe mixed with doubt and hope that they are “doing the right thing.” With the birth of subsequent children, the feelings are more settled, and preparations become more routine. The special excitement and wonder accompanying the birth of the firstborn male is captured in Judaism in the special ceremony for the redemption of the first son, pidyon ha-ben.
One explanation given for this commandment is that it commemorates the great miracle that took place in Egypt when the Almighty killed all the firstborn Egyptian males and spared the Jewish sons.
Furthermore, the firstborn male child has special rights concerning inheritance and a certain religious obligation to fast on the eve of Passover. This stems from the historic fact that the Almighty sanctified the firstborn males of the Jewish people while they were still in bondage in Egypt, so that they would devote their lives as priests in the Tabernacle and the Temple.
This is interpreted by Eliyahu Kitov [in his book Man and His Home] as a reward for the faith and trust in God displayed by the Jewish people, who fulfilled the commandment of circumcision and the Passover sacrifice while in Egypt and under the difficult conditions imposed upon them. As the entire nation proved their loyalty to God by joining the covenant, the Almighty did not isolate the entire nation for the priesthood but only their firstborn, as it is written: “Sanctify each firstborn male child to Me, among the children of Israel.”
However, since the firstborn males joined the nation in their act of worshipping the golden calf in the desert, the Almighty replaced them with the Levites, ordaining: “And each firstborn male child shall be redeemed” and “And you shall take the Levites for Me, the Almighty, instead of each firstborn male child in Israel.”