Holy is Qodesh, To make holy or to sanctify in Hebrew is the same word.
Ex. Gen 2:3, He sanctified or set apart the 7th day. Something made by God or set aside by God is Holy, it is God that makes something Holy, his presence and his spirit make something holy. (Isa. 62:12)
Unholy is ”Chol” simply the opposite of Qodesh. (1 Sam 21:5) The use of the English profane often makes something seem to be wrong with Chol yet it can and does often only mean something is not set apart for service or use of or by God. For example (Eze. 48:15) your translation might say profane Like KJV yet here it is simply common or ordinary, so unholy does not always mean evil or bad as is often thought mostly because of translations into Latin then English which mars the actual meaning.
Clean ”Tahowr”, from taher. To cleanse or purify physically or ceremonially, Yet when used of objects like gold it means pure. (Exo 25:17) Clean is not holy. (Gen 35:2)(7:2)
Unclean or ”Tame” is to be defiled (Gen 34:5) with things like idolatry or ceremonially defiled. Touching a live unclean animal for example does nothing, it is a result of some action such as touching the carcass of dead unclean animals hence the animal is not unclean in its live state only in death so no sacrifice or slaughtering to eat was allowed since the killing of the animal made it to become contaminated and therefore not fit for certain things. (Lev 11:24;31)
So simply put holiness is of God, cleanliness is of man.
Animals originally were very good in the creation account. The result of sin changed things for men and animals. Animals or insects are in no way unclean in and of themselves, (Rom 14:20) it is death that brings on this state. Whatever God's reasons for specific animals being clean or unclean we are not told. Note that even clean animals become unclean at certain times like when one is strangled or dies of old age it is not allowable for consumption, only when prepared correctly is it now clean, or when sacrificed properly was it clean, death plays a role in this determination no matter what the situation. So nothing created is unclean until man takes action.
Now the Greek, Hagios is Holy. (Matt 4:5) It is the word in Greek used to carry the thought from Qodesh in Hebrew.
Koinos is the Greek opposite and is Common or something not set apart for use by or in the service of God, therefore not Holy or Hagios. (Rom 14:14)
The Greek for clean is namely Katharizo and Katharos. (Rev 19:8) This is something that has been cleansed, the opposite is Akathatos and means not cleansed.
In The English translations, there is a translation issue, it is found more so in KJV but is in others too. At times it shows this word Koinos as being opposite of holy or as Common and it also translates this same word as unclean. Even our dictionary, and other Biblical resources have taken these old translations and use them incorrectly. This is because of the way the Greek was translated into English originally. We can see just one example in Romans 14:14) looking into the words of the Greek when you see clean or unclean, common or uncommon, and holy and unholy is important in order to get the proper thought being given us by the original writer.
Let's look at an interesting pattern now that we can gain from viewing Torah in a spiritual sense as it is and not in the sense of physical works based as it is often thought to be.
Read Lev. 10:8-11) The thought is knowing and teaching the difference between Holy and unholy, clean and unclean.
There is a pattern here, the fact that God wants our obedience, and also wants us to trust him. Therefore, faith and trust in God is our willingness to accept God's word without questioning his motives. When we repent or turn away from sin, we are told to put on the mind of Christ, put on the new man, to renew our minds.... Soon, we allow God's Word and his spirit to make these changes, which leads us to change our conduct, to a clean way of living, which allows God to make us Holy. We cannot be holy, God must make us holy, he cannot set us apart for service to him as holy while we are in an unclean state! The priests were given this instruction and ARE WE NOT PRIESTS? Had we not sinned, then repentance would not be required, before sin there was no unclean anything.
Now, look at Eze. 22:26) The religious leaders here are being chastised for not showing respect for, or teaching about things God has set apart and made holy. Application to the priesthood in our day? I would say yes, consider all those who are part of the so-called church who confess and also claim to be repentant and set apart for God yet are still taking part with the world in its ways and are not living a life of conduct befitting Gods people, this is not just the members but the leaders specifically who lead and teach. It begins with those who teach when they teach the flock things contrary to God's word and leads those who blindly follow into a life of wrongful conduct and unscriptural teachings they will be judged even more for these things they do and in most cases willingly.
Yeshua came to fulfill the law, he taught the deeper spiritual things of the word, which brought us more understanding of living by faith and not by works. Paul continued these things in great detail, but stating that the law is spiritual, but we are fleshly, and he made sure over and again to state that it was faith and the understanding of the deeper things of the word, as taught by Yeshua that gave us an understanding of what holy conduct and clean living truly is. When we drop the very words of God from our study, and teaching, we begin to rely on our own understanding of clean and unclean, holy and unholy and not on what God has given us for that understanding, HIS Word... This of course applies to all subjects not only this one.
I have done this word study as a companion to my 4 part talk on what sin is according to scripture. As I stated before this is not about whether we are or are not under the law, that is fleshly thinking, it is about how we live and what our standard of living is. God's standard which is given in a spiritual law or our own which is according to the law of sin which is of the flesh. God has one standard for his people which now include ALL who have put faith in Messiah, all who are now Israel whether physical or spiritual, the Bible says there is no more Jew or Greek, slave or free, (Gal 3:24-29) there is no more kingdom of Judah and Israel, not even physical Jews are Israel according to scripture but only those who put trust in God and Messiah Yeshua. (Rom 2:12-29)(Rom 11:17-25)
If we cannot come together and stop dividing (2 Tim. 3:14-17) Gods word (Eph. 4:4-7) and ourselves by stating that we are or are not Jews or gentiles or protestant or catholic or Christian or allow our church doctrine or tradition to divide the Word of God and to divide his called out believers into factions based on separate statements of faith and arguments over matters not directly given in Gods own words then I am afraid that things will only be that much more difficult when the great time of trouble and persecution begins.