Monica I agree, everybody's interests and abilities are different - some are very good at languages, others at maths, sports, science, art, music, etc. etc. Some are very fortunate in being able to excel in many academic and other areas, whatever their background.
I don't think many people would argue that everybody is equal in terms of intellectual/practical/physical abilities. However, I think much research has indicated that, bar those with exceptional abilities in one or more areas, a lot of the difference in academic outcomes are a result of unequal access to a number of things which influence learning. These include: secure housing and enough room to study quietly, regular and nutritious food, access to outdoor play and nature, days out/holidays in this country or abroad, well equipped schools with motivated teachers, access to private tuition and extra-curricular activities such as learning a musical instrument, etc. etc. etc.
I think it is too easy (and convenient for some) to equate academic and career success with higher inherent intellectual ability and hard work. Whilst there will always be gifted individuals, I believe that, generally speaking, educational and career outcomes are more dependent on external factors than individual ability. Because these inequalities are not addressed, it seems to me that there is a great pool of unrealised talent and sometimes people in high office who are unequal to the job.