If you start a few verses earlier (Genesis 8:21) when God begins speaking, he starts off by observing Noah’s actions of killing the animals and burning their bodies and God responds by saying that every inclination of the human imagination is evil. Then he tells Noah and his family that the animals will be afraid of them and that they will see the animals as food. To me this sounds a lot more like a warning than permission. God even references the “pleasing aroma” much like the fruit from the forbidden tree that is described in Genesis 3:6 as “pleasing to the eye”. I think a much more genuine reading of Genesis 8-9 is that God is describing the consequences of us following our own sense pleasures and our own evil imaginations rather than following God’s “very good” instructions (Genesis 1:31).
Noah followed all God’s instructions to build the ark and include every kind of animal in it and God saved him and his family and all the animals aboard the ark (Genesis 6:22). But then upon exiting the ark, there is no instruction anywhere in the text for Noah to kill and burn the animals. In fact, this is the first time in Genesis (and therefore the first instance in the Bible) where mention is made of an altar being built and animals being burned on it. Instead of waiting for God to give him further instructions, as far as I can tell from the text, Noah took it upon himself to build an altar and to kill and burn the animals on it. And just like Abel’s slain blood “cried out to God” from the ground after Cain killed him (Genesis 4:10), the smell of the burning animals made its way to God’s nostrils after Noah killed and burned them (Genesis 8:21). Just as Cain’s action of killing his brother was a deviation from God’s instructions, so was Noah’s action of killing the animals.
Despite Noah being described as a “righteous man” who “walked faithfully with God” (Genesis 6:9), his deviation from God’s instructions after exiting the ark prompted God to describe every inclination of his heart as evil (Genesis 8:21), which was exactly the same phrase God used to describe humanity just before the flood (Genesis 6:5). Given that Noah was described as righteous and faithful, yet still somehow had perpetually evil inclinations in his heart, it really brings to life the passage in 1 Corinthians 13:2 where Paul says, “If I have the gift of prophecy and understand all mysteries and all knowledge, and if I have all faith so that I can move mountains but do not have love, I am nothing.” Based on this closer examination of Genesis 8-9, it seems clear to me that despite Noah’s faithfulness, something was lacking in him that caused him to kill all the animals without being instructed by God to do so, just as something is lacking in a person who points to God’s warnings in Genesis 8-9 as justification for withholding their love from any of our fellow covenant recipients – including the animals that were all mentioned by God as recipients of the covenant promise in Genesis 9:9-10.