I would like to suggest that the oxygenation of Earth's atmosphere wasn't exactly a benign occurrence that life then learned to use. The emergence of free oxygen due to photosynthesis was a devastating mass extinction event! Life didn't just "learn" to use it, the vast majority of life died or was forced into special ecological niches where oxygen didn't or couldn't exist while new organisms evolved to tolerate and then actually use oxygen as a energy source. This mass extinction lead to all complex life on earth.
Metabolism is key. Early life didn't need oxygen but eventually life found an ingenious way to utilize oxygen for metabolism through photosynthesis.
I'm not trying to be pedantic but this is just not an accurate description of how oxygen was or is produced or even what oxygen was. Oxygen was a waste product, life didn't just not need oxygen, oxygen is a poison to anaerobic life! Oxygen caused a mass extinction event!
Also, this is simply not what photosynthesis is, how it works, or how the use of it evolved "but eventually life found an ingenious way to utilize oxygen for metabolism through photosynthesis." this is just backwards and twisted and suggests oxygen was just a benign substance that appeared not to mention that metabolism doesn't always need or even use free oxygen! Also photosynthesis does not utilise oxygen it produces oxygen as a waste product, oxygen metabolism utilizes the oxygen photosynthesis produces.