If you make a job posting, get 5 applicants, interview 3 of them and hire 1 it's hard to point a finger and say you did (or didn't) do anything wrong.
But let's say over the course of a year you receive 10,000 applications for various positions and 15% of those are African American. Now say that 10% of applicants get to the interview stage but none of the African American applicants made it to the interview stage then, in the very least, that looks bad. You would need to justify why that's the case.
Discrimination can be subtle. A lot of people who are discriminatory but don't think they are. In the US, for example, you have what are called "second syllable names". These are names that are traditionally AFrican American (eg Lakisha). I vaguely recall reading a study where someone took a bunch of resumes for assistant positions and for a bunch with "first syllable names" they replaced just the name with "second syllable names" and there was a statistically significant decrease in response rate.
So your personal discretion doesn't extend to unlawful hiring and firing practices.