What do you think the Great Filter is?
The Great Filter is the idea that, in the development of life from the earliest stages of abiogenesis to reaching the highest levels of development on the Kardashev scale, there is a barrier to development that makes detectable extraterrestrial life exceedingly rare. The Great Filter is one possible resolution of the Fermi paradox.
https://en.wikipedia.org/wiki/Great_Filter
The Fermi paradox is the discrepancy between the lack of conclusive evidence of advanced extraterrestrial life and the apparently high likelihood of its existence. As a 2015 article put it, "If life is so easy, someone from somewhere must have come calling by now."
https://en.wikipedia.org/wiki/Fermi_paradox
Personally I think it's photosynthesis. Life itself developed and spread but photosynthesis started an inevitable chain of ever-greater and more-efficient life. I think a random chain of mutations that turns carbon-based proto-life into something that can harvest light energy is wildly unlikely, even after the wildly unlikely event of life beginning in the first place.
I have no data to back that up, just a guess.
We have had Millions of years of (presumably) intelligent Dinosaurs on this planet, but only 200.000 years of mankind were enough to create Civilization IV, the best Strategy game and peak of life as we know it.
So clearly, Civilization™ is what sets us apart.
Jokes aside, the thing evolution on earth spend the most time on is getting from single celled life-forms to multicellular life (~2 billion years). If what earth life found difficult is difficult for all, multicellular collaboration is way harder than photosynthesis, which evolved roughly half a billion years after life formed.
Sort of fallacious to go from one case of time to happen and derive probability from it.
I'm no biologist but I don't think any of our models of super early stuff are sophisticated enough to speculate on what stages are the most or least likely.
You are correct, but that doesn't mean I can't speculate about it.
The ability to do photosynthesis is widely distributed throughout the bacterial domain in six different phyla, with no apparent pattern of evolution., according to this random paper I found on the internet (I'm not a biologist either).
What I can glance is that photosynthesis has (probably) evolved independently 6 time in Bacteria and 3 times in Eukaryotes.
Plants evolved to photosynthesise after photosynthesising bacteria already existed for billions of years.
(But then we have to also acknowledge that multicellular life evolved like 25 times in Eukaryotes, and the Eukaryote - aka Mitochondria-"Powerhouse of the cell"-haver- is the real big step as it only happened once to our knowledge).