The most correct order of the theorized evolution of life on Earth is:
Single-celled organisms produced methane, cyanobacteria produced oxygen, multi-cellular organisms began to form, fish, amphibians, reptiles, and then mammals.
This order reflects the progression of life from simple single-celled organisms to more complex forms, with cyanobacteria playing a crucial role in oxygen production and paving the way for the evolution of more complex life forms.