According to the Old Testament laws regarding punishment and retribution for a crime(sin), when one was assaulted, robbed, murdered...., the responsibility to bring the criminal to justice and to protect the lives/property of the relatives fell to the nearest "kinsman". This responsibility/obligation was referred to as "redeeming", and the man who had this role was called a "redeemer"('goel' in Hebrew). Thus, the LORD God would use this object lesson to teach that redemption(to buy back/release for the purpose of setting free) is provided by a kinsman redeemer. The kinsman redeemer is someone who is qualified to execute the law of redemption-he is qualified to pay the price of debt. This kinsman redeemer of the Old Testament was a "type" of the Lord Jesus Christ as the Redeemer. There were 4 requirements for redemption, one of which is:
The redeemer must not be compromised by his predicament, i.e., the redeemer must be free from that which caused the need for redemption. Thus, the redeemer could not redeem himself. No slave, for example, could redeem another slave. A person in bondage was in no position to redeem another. This explains the virgin conception. This REQUIRES that the redeemer be God. The Lord Jesus Christ "...knew no sin...."(2 Cor. 5:21-see also 1 John 3:5, 1 Peter 2:22, Hebrews 4:15, John 8:46, Exodus 12:5="YOUR LAMB SHALL BE WITHOUT BLEMISH(emphasis mine)". Only God fits this REQUIREMENT.