Two Jewish commentaries offer no definitive explanation. The speculation in the preceding posts are probably the best ideas that are possible at the moment.
Matthew Henry’s commentary does not mention this subject.
There is a literary note, that there is evidence for two intermingled accounts of Noah’s flood here, based on the contradiction of taking seven pair of animals into the ark versus taking one of each kind.
The reference to “clean” and “unclean” sounds like a ritual requirement and underpins that section as coming from a priestly source, according that hypothesis.
I was glad to read that you sourced Matthew Henry - I look at his commentary for information, also.
as for clean and unclean animals - I have several other questions about that section of Genesis, chapter 5:1 " When God created mankind, he made them in the likeness of God. 2 He created them male and female and blessed them. And he named them “Mankind” when they were created. " - isn’t the name for Adam - mankind (Heb. adam, “man” or “mankind”) and also doesn’t this verse reflect on Genesis 1:27 “27 God created man in the image of himself, in the image of God he created him, male and female he created them.”- the first account of creation and not Genesis 2:22 “22 Yahweh God fashioned the rib he had taken from the man into a woman, and brought her to the man.
23 And the man said: This one at last is bone of my bones and flesh of my flesh! She is to be called Woman, because she was taken from Man.” some say that the 1st account is the more spiritual as the 2nd account is the flesh? Would like some thought on this.
Also, toward the account of the animals brought into the ark by Noah, “Genesis 8:1 But God remembered Noah and all the wild animals and the livestock that were with him in the ark, and he sent a wind over the earth, and the waters receded.” and then in " 13 By the first day of the first month of Noah’s six hundred and first year, the water had dried up from the earth. Noah then removed the covering from the ark and saw that the surface of the ground was dry. 14 By the twenty-seventh day of the second month the earth was completely dry."- so just like at the beginning of creation, God’s Spirit hovered over the waters, " 1 In the beginning God created the heavens and the earth. 2 Now the earth was formless and empty, darkness was over the surface of the deep, and the Spirit of God was hovering over the waters." Could this have been how creation started?
and last, regarding the unclean and clean animal - Noah and his family were told that they could eat the flesh of animals - which wasn’t done prior. So not only did Noah offer the clean animals to God for sacrifices (
Genesis 8:20) but also he was allowed to eat meat, but only clean animals. (Gen. 9:3, 5) does this prelude to Deuteronomy 12:20 as well as Deuteronomy 19 (later - on innocent blood,then you are to set aside three more cities. 10 Do this so that innocent blood will not be shed in your land, which the LORD your God is giving you as your inheritance, and so that you will not be guilty of bloodshed.11 But if out of hate someone lies in wait, assaults and kills a neighbor, and then flees to one of these cities, 12 the killer shall be sent for by the town elders, be brought back from the city, and be handed over to the avenger of blood to die. 13 Show no pity. You must purge from Israel the guilt of shedding innocent blood, so that it may go well with you. )
As everyone else has asked, what was the purpose to bring unclean animals into the ark? - the only reference that I can come up with would be in the distinction between, in Leviticus 11