A scientist that writes an article, uses different letters and words to compile his or her final work, however if the scientist uses a single letter to fill up the pages of his work, it can no longer be considered an article nor will it have any value or significance.
The differences in each of the letters of the alphabet cannot be considered oppression to the alphabet. For example, if we look at the word “SON”, the S is curved, the “O” is round and the “N” has three lines joined to make up the letters. The formation of the word “SON” is made up of these letters and the letters are placed in such an order to make up the word that gives its meaning. None of these letters have the right to object to its author… e.g. the “S” cannot complain and say why am I crooked while the “O” is nice and round, nor can the N complain about its sharp edges because the other two are smooth and without any corners.
Oppressing the letters, rather, comes in play if we give a letter a different sound, like call “S” a “D” or if one writes a letter incorrectly, such as joining the ends of a “C” to make it look like an “O”. But if each letter is created as it has been and from each of the letters a sound is formed from which we expect, that is not oppression.
If a large carpet is cut in to smaller pieces with scissors; that is oppressing the carpet that was once large and beautiful, because its value was in its size and we have taken that away from it. However, if we have many small carpets woven to start with then that is not oppression, as each of the carpets have their own perfection and completeness.
No one would complain to a manufacturer of plate-ware as to why small and large plates were made because each plate is manufactured in its own size and for its own purpose, and no plate was broken down to the size of another.
Likewise, differences in the creation of mankind is a based upon the Divine Wisdom, not so that anyone is oppressed, but that from everyone is an expectation based upon their abilities given to them and nothing more.