That's an interesting turn of phrase, because in most cases, we apply the maxim that all things are not equal in the first place. What does it mean, precisely, for two or more items to be equal? If we turn to mathematics as our guide, then equivalence is stated as the values on both sides of an equation carrying the same value, e.g. 3 + 2 = 5, because both sides are equivalent to 5. I know, that's a simplification, but for purposes of illustration, it's all we need.
For in mathematics, equality is a given. Though the numbers on both sides of the equal sign are different, their intrinsic value (after operations) is the same. And one 3 or 2 is as good as any other 3 or 2, and can even be broken down further. You can make both sides of an equation as complex as you like, and in the end, if the value each equation reduces to is the same, they are equivalent.
People are not numbers, nor are they quantifiable as such. The complexity of mind and body is not reducible in the way arithmetic equations are. You cannot be summed up as a single value, though many people will try (credit agencies, MENSA, numerologists). Furthermore, logic dictates that you cannot be compared to someone else on the basis of a single value if one does not exist.
The logic may be irrefutable, but that has not stopped people for eons untold from attempting to paint others with just that kind of singular, and myopic, stroke of the brush. Take any current aspect of humanity, whether it be the obvious (skin color) or the subtle (religious faith), and an inordinate amount of effort is spent trying to quantify, and thereby catalog, those differences in such a way as to give one group a higher value than another. White trumps Black. Man trumps Woman. Catholic trumps Jew trumps Muslim.
That is not to say that there are no differences between individuals -- far from it. As is so often written, we are no more alike than snowflakes, given where we live, from whom we descended, how our genes were expressed, and under what conditions we were raised. More than six billion of us, and we are bundles of minute variations, and yet those variations, at the heart of it, are controlled by physical and chemical processes that operate on a universal scale. We are built of the same types of atoms, using the same chemicals and their reactions, controlled by the same system, DNA. We are all the same under the hood.
It is the superficiality of our differences and the essence of our humanity, that makes the constant striving against equality between people an enigma. If we can be trained to see other people as different from us in some way, we can also be trained to see them as exactly the same. This does not necessitate disposing of the differences between us, only disposing of the acceptance of these differences as some absolute, some quantity that forever holds each of us in a certain place in the natural order. Unlike the elements of the Periodic Table, we are not so easily pigeon-holed, nor should we be. It is not enough to identify ourselves as belonging to some group, unless we also admit to the fact that we are part of a greater group: humanity. If we can train ourselves to look past the glassy surface to the cool, deep waters beneath, we will see more than water, but life. If we can accept that our differences separate us in name only, but not in common fellowship, perhaps we can learn to live and work together towards the betterment of all humanity.
A human can dream, can't he?