You’re missing the larger point. It isn’t about individuals.
If your parents and grandparents were from an ethnic/social/other group that did not have access to resources, then there’s less chance that you grow up in a household that values education or have resources like food, time with parents and caring adults, emotional support and, financial security and so on. These affect your academic success irrespective of how talented or smart you might be.
Providing better access to higher education for people from such groups is a way to make sure that their children don’t grow up in the same environment and the problem is solved over generations.
Such measures of equity are always stop gap measures to address problems until you find grass root level solutions. Right now say protected groups might be first Nations or African Americans. In the future that might change to immigrants from Ukraine or Honduras.