Why would a manager hire an applicant he deems „unworthy“?

A few months ago I had a panel interview with 3 managers for a (technical) working student job. During the interview I had the feeling that the female hiring manager didn’t consider me good enough or passionate enough for the role since she was very fake nice with me and didn’t seem happy about my answers. A day later however I got the offer but after having worked in the department for 2 months I still think she still dislikes me and only chose me because I am a woman in stem. Do you really think this is likely?

Why would a manager hire an applicant he deems „unworthy“?
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