Because all our separateness in personal choice doesn't stop us from being harmonious unless individually we let it. Variety is the spice of life. If we were all the same in attitude it would be boring. But He did give us a guide book to teach us how to get along together if we use it (the bible of course).
If you wish to have a uniform universe, it will be hydrogen atoms. If you wish diversity, you let suns form to provide heavy elements. And if you wish to have a diverse biosphere, you allow for genetic recombination. The record of the universe is one of diversity. This must be seen as a meta-principle since it is present everywhere we look.
We were created in HIS image. I think it defines that GOD is ALMIGHTY. Think about it; if we were all created alike we'd all be one gender one thought and all doing the same thing. GOD was us to be pro-choice; choosing to follow HIS will.
No God created human beings. Human created god in his own image. Gods are the sum total of human superstition. Every god is created upon the moral principals of the people that created gods. God is not the "cause" of human attitude, character or lifestyle rather god is the "result" of those human traits.