I think you are speculating.
How come you don't believe in quite adequately founded evolutionary theories, and yet persist in unfounded speculation so as to keep your faith in god?
Sorry to give you a hard time D.
You use some of the same logic I did, and I am making the assumption you are at the same stage of realisation that I was when I used your logic to retain belief in god...
As to the correctness of your post, natural selection and survival of the fitest are just ONE of a variety of evolutionary mechanisms. The fact you suggest that more factors need considering is a big giveaway. There are loads of factors that have been theorised about, and I am surprised you don't know some of them, given you've been trying to educate yourself about non-god origins.
I think it is unwise to critisize something you've obviously not even investigated it adequately! If I were to make comments here about the Bible from a position of ignorance, I would be lambasted for it by those who know more than me. Consider yourself lambasted in a friendly, fluffy way!
Population expansion is limited by resources; we clever monkies are capable of great utilisation of resources, and have not reached the point where population is limited (globally) by resources running out. Other species can't cope with finding new resources and are far more limited by shrtages.
That's why we are at the top of the pyramid; we're very good at surviving, and that's because of our big brains.
People living in glass paradigms shouldn't throw stones...