They said is the only one doing her job. Anyone in the comp can apply for my job but no one gets to apply for hers. Is this legal?
Sure, it is. There is no right or entitlement to a job in Georgia and employees can be terminated for any or no reason (with few exceptions such as unlawful discrimination). A business certainly does not have to (possibly) terminate a good employee when it fires a bad employee. That would not make sense (except to union or government management).
Workers' Compensation Lawyer
In Georgia you can be terminated, re-assigned, changed to a different job or reduced to part-time at the whim of the employer, unless you can prove the action was taken against you as a result of Federally prohibited discrimination, such as age, race, gender, religion, creed, sexual orientation, etc. If all of the employees of the company are being required to make these same changes then you will have a hard time proving the action was taken against you personally because of prohibited discrimination.