God is Creator. He does not call Himself the Father of the cows. That is your title. God gave man flesh to eat. You don't like it, but He did. He just did not give the blood to man to eat.
The KJV isn't consistent with it's use of 'kill'. But these are two Hebrew words. The latter one is a word that means 'slay.' Exodus 20 says not to murder, (ratsach) a man. The verse from isaiah66 there says he that slays an ox as if he who sacrifices a man. The words are different in Hebrew- schachat and another word that is used for sacrifice, as if these Israelites slaying oxen were like human sacrifice. But the point is NOT that it was wrong to sacrifice oxen... as the Lord had commanded... but that their sacrifices were unacceptable. God did not like idolatrous or otherwise sinful people living lives of rebellion, then sacrificing to him.
And 'schachat' shows up elswhere when God COMMANDS Israel to slay an animal, like in Exodus 12:6
And ye shall keep it up until the fourteenth day of the same month: and the whole assembly of the congregation of Israel shall kill it in the evening.
Do you even really care what God wants, or are you just using religious language to promote animal rights? Or do you think you have some kind of mystical power to determine some parts of the Bible false and some parts true?
The word shows up here in Exodus 12:21 when God COMMANDS slaying a Passover lamb
Then Moses called for all the elders of Israel and said to them, "Go and take for yourselves lambs according to your families, and
slay the Passover lamb.(NASB)
Israelites would kill an animal if they did not want to sin against the Lord by disobeying.
I don't know if you cannot figure out the sense of these verse or if you are intentionally just trying to take verses out of context to support your agenda. This is a commentary for you to read to help you get a sense of it. Notice that 'abominations' often refers to idolatry in certain contexts, or the idols themselves.
You can find the following commentary at:
https://biblehub.com/commentaries/isaiah/66-3.htm
I think it will give you a good idea of the gist of the verse, if you care to understand something.
My brother is not an ox or a monkey. Also, don't call your mother a cow. You should honor your father and mother.