1. Lung cancer in smokers is not primarily caused by formaldehyde. There are lots of other irritants/carcinogens in tobacco smoke, chronic exposure of which contributes to cancer. Non-smokers are exposed to formaldehyde in comparable quantities to smokers from various industrial processes, household solvents, etc.
2. Rhabdomyolysis in burn victims is caused by the reperfusion of massively damaged muscle tissue.
3. The breakdown of muscle tissue in rhabdomyolysis releases creatine kinase, not creatinine.
4. Creatinine does not have antimicrobial effect at concentrations available in the human body. You would need to increase its plasma concentration 100-fold to get an appreciable effect on microbes. Suffice to say, that would be quite unhealthy for your kidneys.
Where did you get these ideas from? r/nootropics?