I have a feeling that if race truly played a preferential role in hiring engineers, we would see more than 1% of tech roles being filled by Black engineers at Google. ;)
Without knowing the distribution of the applicants, we can't say. Maybe 0.1% of all applicants are black, we don't know. In the same way, just saying 1% of tech roles are filled by black engineers doesn't imply that google's hiring practices are discriminatory.