“Everything that lives and moves about will be food for you. Just as I gave you the green plants, I now give you everything” (Genesis 9:3).
This is a reference to Genesis 1:29 where God instructs humanity to sustain ourselves on fruit and vegetation and that it is very good to do so (Genesis 1:31). The context of this passage in Genesis 9 is God had just destroyed nearly every inhabitant of the earth with a great flood in order to restart creation anew. As God was blessing each creature (Genesis 8:17), exactly as God did in the initial creation (Genesis 1:22), Noah took it upon himself to build an altar and burn some of the animals on it (Genesis 8:20). This prompted God to describe humanity as being motivated by their own evil imaginations (Genesis 8:21), just as he did prior to the flood (Genesis 6:5).
God blessed humanity anyway, just as God promised (Genesis 6:18), but unlike at the beginning of creation (Genesis 1:27-31), this time God warned humanity of the consequences of following our own evil imaginations (Genesis 9:2-6) instead of following God’s very good instructions (Genesis 1:27-31). In this passage God is telling us that we are given a choice whether to trust in God and follow his instructions or instead to do things our own evil way along with the corresponding consequences. If we follow God, everything is very good whereas if we follow our own evil imagination, the world is filled with fear and bloodshed.
All throughout the bible, God says he gives us a choice: we can choose the path of obedience that leads to life or the path of destruction that leads to death (Deuteronomy 30:15, Matthew 7:13). Chapters 8 and 9 of Genesis are a warning in response to Noah building an altar and burning animals on it. God did not instruct Noah to do this, unlike all the previous things God had been instructing Noah to do. Up to this point Noah had faithfully followed each instruction (i.e. to build the ark according to the exact measurements, fill it with food and animals, close up the door, and then open the door after the flood waters subsided), but this time something changed. God instructed the animals exiting the ark to be fruitful and multiply, just as God had instructed them to do at the start of creation (Genesis 1:22). Noah, however, hindered the animals from following this divine instruction by taking it upon himself to build an altar and burn the animals on it (Genesis 8:20).
As a result of this act from Noah, God warned that everyone will be afraid and kill each other. Re-read that section anew and see for yourself. It is not God changing his mind and granting permission (God does not change, Malachi 3:6). It is God warning of the consequences of disobedience. He even refers to Noah’s act of burning the animals as evil, saying every inclination of his heart is evil (Genesis 8:21), which was the same pronouncement God made on the earth which led to the flood in the first place (Genesis 6:5). God says this about Noah even after Noah had faithfully followed all his instructions prior to this unprompted act to build an altar and burn animals on it. In fact, due to his obedience Noah had even been referred to as righteous (Genesis 6:9, 7:1), but after the act is referred to as following the evil inclinations of his heart rather than following God’s instructions.
Lastly, if we assume God stopped caring about animals and decided they were now just food items, as some interpreters suggest, God would not have included them in the covenant promise in Genesis 9. But instead God mentions animals FIVE times as being recipients of the same promise granted by God to Noah and Noah’s family (Genesis 9:9-10, 9:12, 9:15, 9:16, 9:17). God does not make covenants with food (i.e. plants) but only with those whom God loves. God loves people and animals, and this is not the only time God makes covenant promises of safety to animals (Hosea 2:18). It is up to us whether we choose the path of following our own evil imaginations (i.e. the forewarned path that leads to fear and endless killing), or the path of obedience to God’s original instructions (i.e. the path of love that leads to life). God gives us the power to make that choice.