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.

Therefore, creating interactions of realities does a lot to end sin. Reason is the most controlled way of doing so, since it is a process of consciously pointing out relationships between realities.

There are also a lot of interactions that occur automatically and unavoidably in material life. The interactions automatically cause truth to increase, which in turn diminishes sin.

One thing that promotes the interaction of realities is diversity. As long as diverse realities exist, they will come together to create interactions. Bringing them together is more or less automatic. It is the existence of the diversity that is critical and not so automatic.

Therefore, God creates a lot of diversity. Out of the diversity, realities interact, which creates truth, which ends sin.

A major example is Protestantism. It gave a lot a Christians the freedom to oppose the official realities of Catholicism. One of the first consequences was that it forced Catholics to do a lot of house cleaning. Catholic authorities had to be more credible and tolerant of the concerns of the peons (they would say "the faithful") because of Protestantism.

Conservatives assume that everyone should think the way they do, and they are on a relentless quest to force them to do so. Conservative Protestants strive for a theocracy where everyone believes what they do. Conservative Catholics think no one will get saved unless they become conservative Catholics, and they can't understand why so few persons are.

Only persons who are dead to 99.9% of all sin could assume that agreeing with themselves would end the problems. Human existence can only be managed corruption, and the best way to manage it is with a lot of diversity.

One indication of that fact is that corrupted persons are obsessed with homogenizing the world. They cannot tolerate differences. They want everyone to be the same, so they can control them all by pulling one string. If one person out of five billion is allowed to dissent, too much truth gets established.

It is for these reasons that God created several major religions instead of just one. They can't all be producing different truths; there is only one truth. But none of them are producing perfect truth. It's impossible to even convey truth perfectly through material communication. And realities never enter two minds in exactly the same way. So perfect truth is abstract, it's not a material entity.

God only develops theological complexities in one place, which is Christianity. He used four thousand years of systematic evolution to develop Christian theology. Other religions do not have a theological purpose. It would be ineffective to try to develop complex theology in societies which do not have highly developed educational systems and libraries and environments oriented towards their use.

For example, the Moslem religion is oriented towards worship and discipline. Those things can be developed better without theological complexity. The western world used theology to corrupt religion, not to purify it. Out of that corruption some truth evolves, but it doesn't purify anything.

It's ok for middle eastern and eastern persons to become Christians, if they can relate to the subject, but their native religions are generally more appropriate for their social environments. Conservative Christians cannot understand how all those religions can create one shepherd and one flock, but they have their heads in the concrete. The material world is never going to be one shepherd and one flock; it's a spiritual concept. And the truths that unify are more apt to be produced through everyday life than in the seminaries.