Strongly recommend a book by a couple of confirmed evolutionists called 'Rare Earth', which gives the evidence that there may not be any other planet anywhere which is hospitible to life.
Rare Earth
Peter D. Ward
Donald Brownlee
Copernicus, New York
2000
And Helix, oh Helix.... you have swallowed so much so blindly...
Oxygen is not a poisonous gas. It is the garbage collector of our systems. Free radicals of oxygen are not good in our system because that means there is more of them than of the processed carbon and hydrogen that needs to be disposed of so it tries to grab on to other things.
But it is also what is in those green cannisters the sick people breathe from! They are not breathing poison.
In addition, there is NO NONE ZIP NADA evidence in the rocks that the earth was ever without oxygen. In fact, no matter how far back they go, they find oxygen.
You have repeated some disproved evolutionary storytelling.