Vaccination is about a lot more than just yourself. There are people everywhere who legitimately cannot be vaccinated, for various health reasons. The entire concept of herd immunity (the actual, defined concept not the news media and Facebook concept) is that if you get a large enough percentage of the population vaccinated, then the folks who can't get vaccinated are protected. So a school district, hospital, or any other general employer who requires vaccination is basically doing that so that they are creating an environment that is safe for everyone, including the handful of students, patients, or employees who are genuinely unable to get the vaccine.
Just a hypothetical, but let's say two people file a lawsuit against the same employer. One files a lawsuit saying that they should not be required to be vaccinated because the employer cannot control what happens to their body. Another files a lawsuit saying that because the employer does not require vaccination, the workplace has become hazardous because that employee cannot be vaccinated. I wonder which would win.
And no, masks do not provide nearly the same protection as a vaccination. I challenge you to show me where any actual public health authority (e.g., CDC) has ever published that. Masks are meant to slow transmission, but to nowhere near the same degree as mass vaccination.