Its a fair question. But yes, it is hard to keep such a topic focused.
First, what do people mean when they say "all men are created equal"? I really have no clue what people mean by that in today's world. It seems like it is one of those American leftovers from another time when we actually understood what such things meant but has now become a much-loved but meaningless phrase we toss around. Some are better athletically, musically, intellectually, socially, and so on than others are. Some people seem to be strong in almost all areas and others seem to be weak in most, while most are mixed somewhere in the middle. There does seem to be a bell curve in giftedness (though definitely not the way the infamous book "The Bell Curve" puts it). I believe the way it was originally used in the formation of America was to say "The intrinsic value of all people given by God is equal".
If we take this equality thing to mean on a purely worldly scale, it can be disproved. If however, we look at it as equality before God that is something quite different.
The most quoted scriptural basis for the belief in equality under God is Galatians 3:26-29 "For you are all sons of God through faith in Christ Jesus. For all of you who were baptized into Christ have clothed yourselves with Christ. There is neither Jew nor Greek, there is neither slave nor free man, there is neither male nor female; for you are all one in Christ Jesus. And if you belong to Christ, then you are Abraham’s descendants, heirs according to promise.
I think this passage from Galatians is also one of the most misquoted scriptures. Many times I have heard people quote this and then go on to say that husbands should not be the head of the house. It is not advocating that men and women are the same, or that the roles of slaves and free people are the same. It is saying there is equality under God. In the sense of day to day living it is not advisable for a slave (or employee) to treat their master as a fellow servant. But it is advisable to understand that we are equal before God and that each person is responsible for what they do before God.
So if we ask the question; "are some more gifted in a broad range of things in this life?; I would say "yes". If the question is "will God reward some based on gifting or birth?" the answer is "no, we are all equal before God". What is significant is what we do with what we were given.