"....dead protein from animals that have been killed is degenerated by enzymatic destruction, which makes that protein useless for human cell growth".
I may be missing something that you've said but, I'm fairly sure that animal protein does promote human cell growth. I know several very large people that live mostly on meat, and I believe studies have shown that vegetarian children end up with a smaller stature.
I'm certainly not advocating meat-eating here, I just want to be clear on why you would say that animal protein is useless for human cell growth.