False dichotomy. The Church's authority to govern herself --- that is, the "teach-govern-sanctify" mandate --- comes from the Bible. Therefore the properly constituted authorities have the power to make the Church's own canon law.
The current Code of Canon Law took effect in 1983. The former canon law code (1917) was about 1/3 longer --- so a a lot of the old canons were combined or abolished, These canons are rules related to the governance of the Church. Which is to say, the Church has the authority from God to govern herself.
Some of these laws are subject to change, and some are not. For example, the discipline of women wearing a veil at Mass was not kept in the 1983 code, so it's not required. On the other hand, the doctrine that only a validly ordained priest can consecrate the Eucharist, is unchangeable because it has to do with the definition of the Sacrament.
Christ told His first, select Church leaders, “Whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven” (Mt 16:19, 18:18).
"Binding and loosing” is a Jewish phrase that means forbidding and permitting. It described the authority of the scribes and Pharisees to establish rules of conduct for the faith community, and the good Jew was called by Christ to obey them (Matt. 23:3).
In giving Peter the "Power of the Keys," Jesus is giving him the authority as viceroy to govern his Royal Household, the Church, as foretold in Isaiah 22:20-23 (LINK) "On that day I will call my servant Eliakim son of Hilkiah, and will clothe him with your robe and bind your sash on him. I will commit your authority to his hand, and he shall be a father to the inhabitants of Jerusalem and to the house of Judah. I will place on his shoulder the key of the house of David; he shall open, and no one shall shut; he shall shut, and no one shall open. I will fasten him like a peg in a secure place, and he will become a throne of honor to his ancestral house."
That's what the "keys" are all about.
Since Jesus gave this authority to the leaders of his Church, they have authority to do such things as establish feast days, regulate the clergy, and lay down laws for the good of the community.
"It is a policy. It was never God’s plan."
There is indeed a distinction to be made between God's laws (unchanging) and Canon law (some of it changeable) --- but this is understood in the context of Christ GIVING the Church the power to govern His household on earth.
God’s plan was for Adam and Eve and to be fruitful and multiply.
Yes, but He does not say every individual without exception has to marry and have children. Quite the contrary.
Matthew 19:12
"For there are different reasons why men cannot marry: some, because they were born that way; others, because men made them that way; and others do not marry for the sake of the Kingdom of heaven.Let him who can accept this teaching do so."
So this calling was recommended by Christ --- not for everyone, but those who are called, who can accept these teaching, should do so.
St. Paul likewise did not command this vocation for all, yet he highly recommended it. Do check out 1 Corinthians 7, which is certainly worth reading in context.
"So then, he who marries his virgin does right, but he who does not marry her, does better."
There is absolutely NOTHING in the Bible requiring celibacy as a prerequisite for service in the priesthood. Quite the contrary:
“A bishop then must be blameless, the husband of one wife, vigilant, sober, of good behavior, given to hospitality, apt to teach.”
1 Timothy 3:2
CLEARLY clerical marriage is permitted in the Bible. Of course the Church has every right to make up its own rules and regulations. But NO Church has the right to rewrite the Bible or to rewrite history.