Vatican II 22. Traditional Catholicism 31. Veritatis Splendor Other Evolution Spirit World Materialism Art Diversity. There wouldn't need to be so many plants and animals on planet earth, not to mention insects, but God likes diversity. He's quite objective to, and there are objective reasons for it.
Diversity is a basic method of coping with sin.
In terms of principles, one of the pillars of human existence is that sin cannot exist in the light of truth. The simple reason is because sin must be concealed, because people feel threatened by a destruction of life, which is what sin is. Then there is the principle that truth always increases through the interaction of realities. The reason is because consistent relationships support each other, and inconsistent relationships contradict each other, when realities interact. The process is so automatic that no one can defy it.