Pay a visit to the local office of the Ohio Civil Rights Commission or the federal EEOC. You may be the victim of unlawful employment discrimination under applicable state and federal law. It is unlawful for your employer to retaliate against you in any way for consulting with the Ohio Civil Rights Commission or the EEOC.
Your summary suggests both that you are being treated differently from other employees, but also suggests that the manager mistreats other "certain employees." Simply being a bad and uncouth boss might not be unlawful. Such conduct becomes unlawful if it is based on distinctions prohibited by law, such as sex, race or religion. You do not say, but it appears your company might not employ many individuals. If the company is large enough to have a human resources department, you might consider asking for a confidential conference with the HR manager. He or she might be able to approach the general manager to inform him that his conduct is making some employees uncomfortable, or he or she might be able to make some suggestions about what you can do. If there is an HR manager, suggest that he or she investigate what is called "conflict coaching." There are many good resources on the Internet, in particular some applying coaching (one on one discussions) to workplace conflict. If your company is too small to have an HR department, maybe you can get together with the "certain employees" who are victimized by the general manager, have a candid discussion about how they feel, and if some or all of you are in agreement, approach the manager as a group. Make your presentation less like a complaint and more about asking the general manager what he might want done differently and to have him try to appreciate your point of view about work. Even if there is no protection to you under the civil rights discrimination laws, you might be protected under federal or state law for concerted (group) action. Check in your area for "dispute resolution" organizations that might be willing to try to set up a conference with the general manager and the employees. In order to be in the best position, before taking action you might want to consider what other employment you might find if discussions go badly. Sadly, there is no guarantee that the manager will act in a reasonable and adult manner. There always will be a risk to your job. Finally, have you checked to see if there is a union that might be interested in organizing your place of employment?