As someone who’s worked in schools, such requests are virtually never entertained. It is so impossible to balance class size, gender balance, academic abilities balance, distributing kids with special needs, separating kids with explosive conflicts, and managing schedules for things like specials, pull-outs, and medical needs. Also, schools know that some homeroom teachers are often highly sought after and some don’t give families warm fuzzies. Unless the less warm/fun/supportive teacher does something fireable, we’ve got to keep them on and give them students. While you may have what you believe to be “good reasons” for thinking this isn’t a good fit, there are many other parents worried about fit who would also lobby for class changes. If schools took all of those requests, it would be a weeks-long process to sort out, and it would be difficult-to-impossible to develop fair criteria for who gets a class switch.
Accept the assignment and work on what you can control. If your child needs accommodations, schedule a beginning-of-year conference with the teacher and and admin. If there are social issues, get the school counselor’s help before things get challenging. This is also a good opportunity for you and your child to learn resilience and positivity when things don’t go perfectly.