Well if we did not spring forth from them then oxygen would not be considered anything beneficial to maintain.
Considered by who? Maintained by who?
There is evidence that photosynthesis occurred without releasing oxygen as a waste product in other organisms.
There is indeed anaerobic phototrophy in some species, but photosynthesis specifically always produces gaseous oxygen. It's the inevitable result of using water as an electron donor in redox chemistry.
The problem came in when the sun was growing stronger so they were either forced to learn to convert its energy which meant building an ozone layer to protect them in the process.
When was the sun "growing stronger", and why? And what relevance would that have to organisms in
the ocean, who are protected from UV radiation regardless of the presence or absence of ozone?
Creating a multicellular organism that allowed them to maintain the supply of chemical conversions that before naturally occurred from the planet was a solution to the problem.
Who thought this was a "problem" in need of a solution? Who "created" anything? What "chemical conversions" were not being created?
Barbara, you've created a narrative of the natural history of the Earth that is all but completely unmoored from fact, solely so that you can dispute the science of evolution.
But disputing evolution is going to have to occur from a basis of fact, not from fairy tales from pre-history.
™ Version 4.2