Why was John not worthy to loosen the strap of Yeshua/Jesus’s sandal?
John 1:27the One coming after me, who has become before me, WHOSE SANDAL STRAP I AM NOT WORTHY TO LOOSEN.”
John realized that in by saying this, that he was not worthy to be the Kinsman Redeemer. What he was speaking, concerning the sandal strap being loosened, is in reference to not only the kinsman redeemer law mentioned in Leviticus 25, but also the levirate law mentioned in Deuteronomy 25:
•Leviticus 25:25If thy brother be waxen poor, and hath sold away some of his possession, and if any of his kin come to redeem it, then shall he redeem that which his brother sold. 26And if the man have none to redeem it, and himself be able to redeem it; 27Then let him count the years of the sale thereof, and restore the overplus unto the man to whom he sold it; that he may return unto his possession.
•Deut 25:5If brethren dwell together, and one of them die, and have no child, the wife of the dead shall not marry without unto a stranger: her husband’s brother shall go in unto her, and take her to him to wife, and perform the duty of an husband’s brother unto her. 6And it shall be, that the firstborn which she beareth shall succeed in the name of his brother which is dead, that his name be not put out of Israel. 7And if the man like not to take his brother’s wife, then let his brother’s wife go up to the gate unto the elders, and say, My husband’s brother refuseth to raise up unto his brother a name in Israel, he will not perform the duty of my husband’s brother. 8Then the elders of his city shall call him, and speak unto him: and if he stand to it, and say, I like not to take her; 9Then shall his brother’s wife come unto him in the presence of the elders, and loose his shoe from off his foot, and spit in his face, and shall answer and say, So shall it be done unto that man that will not build up his brother’s house. 10And his name shall be called in Israel, The house of him that hath his shoe loosed.(KJV)
This has to do with inheritance and redemption. This is why Yeshua is called the “first-born” as He brings us back to inheritance through Him as the rightful heir; as well as called our “brother” as it has to do with kinship, like of kin. We are made rich, through Him.
•Phil 2:6Who, being in the form of God, thought it not robbery to be equal with God: 7But made himself of no reputation, and took upon him the form of a servant, and was made in the likeness of men: 8And being found in fashion as a man, he humbled himself, and became obedient unto death, even the death of the cross.(KJV)
•2 Cor 8:9For you know the favour of our Master יהושע Messiah, that being rich, He became poor for your sake, so that you might become rich through His poverty.(ISR 98)
There is only One true Kinsman Redeemer, and that is our Creator Himself. There is only One who can purchase the souls of men into everlasting life.
John knowing this, that Yeshua was/is the rightful Redeemer, the rightful heir to purchase and redeem said, “He came before him, even though He also is coming after him”. This was also in correlation to the book of Ruth. John came before Yeshua, however, was not the one who could ‘purchase’.
In the book of Ruth, Boaz came after the initial kinsman, to redeem both the inheritance to Naomi, and also the ‘wife of the dead’ Ruth. Boaz is a type and shadow of Yeshua. 
Ruth 4:4And I thought to advertise thee, saying, Buy it before the inhabitants, and before the elders of my people. If thou wilt redeem it, redeem it: but if thou wilt not redeem it, then tell me, that I may know: FOR THERE IS NONE TO REDEEM IT BESIDES THEE; AND I AM AFTER THEE. And he said, I will redeem it.
5Then said Boaz, What day thou buyest the field of the hand of Naomi, thou must buy it also of Ruth the Moabitess, the wife of the dead, to raise up the name of the dead upon his inheritance.
6And the kinsman said, I cannot redeem it for myself, lest I mar mine own inheritance: redeem thou my right to thyself; for I cannot redeem it.
7Now this was the manner in former time in Israel concerning redeeming and concerning changing, for to confirm all things; a man plucked off his shoe, and gave it to his neighbour: and this was a testimony in Israel. 8THEREFORE THE KINSMAN SAID UNTO BOAZ, BUY IT FOR THEE. SO HE DREW OFF HIS SHOE. (KJV)
Naomi represents the House of Judah and Ruth represents the House of Israel/Ephrayim. The inheritance came from Judah, however, upon the death of Yeshua, the House of Judah became a widow, and the House of Israel had already been divorced(Jer 3:8), and were cast out of His House, out of covenant, out of the land, and out of inheritance(Deut 24:1-3).
(If you would like to read more concerning the houses and the covenants you can go here and here.)
Through the death, and resurrection of Yeshua, both houses had redemption through Him, they could become wed to ‘another’ the ‘next of kin’, the ‘first-born’. Bringing the spiritually dead to life, so that ALL may come into a New Covenant:
•Deut 25: 5“When brothers dwell together, and one of them has died, and has no son, the widow of the dead man shall not become a stranger’s outside. Her husband’s brother does go in to her, and shall take her as his wife, and perform the duty of a husband’s brother to her.
6“AND IT SHALL BE THAT THE FIRST-BORN SON WHICH SHE BEARS DOES RAISE UP FOR THE NAME OF THE DEAD BROTHER, so that his name is not blotted out of Yisra’ĕl.
•Romans 7:1Or do you not know, brothers – for I speak to those knowing the Torah – that the Torah rules over a man as long as he lives?
2For the married woman has been bound by Torah to the living husband, but if the husband dies, she is released from the Torah concerning her husband.
3So then, while her husband lives, she shall be called an adulteress if she becomes another man’s. But if her HUSBAND DIES, she is free from that part of the Torah, so that she is not an adulteress, having become another man’s.
4So my brothers, you also were put to death to the Torah through the body of Messiah, for you to become another’s, the ONE WHO WAS RAISED FROM THE DEAD, that we should bear fruit to Elohim.
This is why when Boaz and Ruth had a son, that brought back the inheritance, it was also a foreshadow to Yeshua:
•Ruth 4:14And the women said unto Naomi, Blessed be the LORD(YHWH), WHICH HATH NOT LEFT THEE THIS DAY WITHOUT A KINSMAN, THAT HIS NAME MAY BE FAMOUS IN ISRAEL. 15AND HE SHALL BE UNTO THEE A RESTORER OF THY LIFE, and a nourisher of thine old age: for thy daughter in law, which loveth thee, which is better to thee than seven sons, hath born him.(KJV)
Which all then just flows perfectly into following verses of what John says after he is not worthy to loosen the sandal strap:
John 1:29On the next day Yoḥanan(John) saw יהושע(Yeshua/Jesus) coming toward him, and said, “See, the Lamb of Elohim who takes away the sin of the world!
30“This is He of whom I said, ‘After me comes a Man who has become before me, for He was before me.(ISR 98)
The purchase price for redemption, John could not pay, but knew of One who could. The One who came before Him. The purchase price for redemption, that YHWH Yeshua paid in His own blood, with His own life.
•Acts 20:28“Therefore take heed to yourselves and to all the flock, among which the Set-apart Spirit has made you overseers, to shepherd the assembly of Elohim which HE HAS PURCHASED WITH HIS OWN BLOOD.(ISR 98)
•1Cor 6:20FOR YOU WERE BOUGHT WITH A PRICE, therefore esteem Elohim in your body and in your spirit, which are of Elohim.(ISR 98)
•Eph 1:7in whom we have REDEMPTION THROUGH HIS BLOOD, the forgiveness of trespasses, according to the riches of His favour,
How amazing is that?
