Race seems to be a significant factor for some of these jurors. What other factors are playing a part for some or all of these jurors?

I think socio-economic stature plays a part. The juror's personal backgrounds and prejudices come into play as well. Consider, for example, the third juror. He proudly says that he started his business from scratch and now employs thirty-four workers. We learn early on that he has a bad relationship with his own son, with whom he is no longer speaking. This heavily affects his opinions about the case.