Every single person who is eligible to vote has his/her own reason for how he votes and even IF he votes.
Biden was a very well known experienced White male politician.
Kamala was a less well known female Black politician. I suppose that there are dozens of reasons and emotional states that caused people to vote how they did. Race, gender, experience and familiarity are the main differences, but emotion also plays a role.
Anyone who voted for Trump because they thought that he would make egg and gasoline cheaper is simply stupid, but here are really people that stupid.
I think that race and gender were the most important factors why people stayed home or voted for whomever, but certainly not the only reasons.