COVID doesn’t “know” anything. Errors happen and it either gives the newly mutated virus a competitive advantage or it doesn’t. If it doesn’t, it doesn’t infect enough people to be noticed since no countries are sequencing 100% of infections. A few countries are sequencing 100% of confirmed positive tests. But that only gives a subgroup. Any mutation that presented with illness that went unnoticed by its host and therefore no reason to test would be missed. So yes, there have been many more variants / mutations than we know about. And they died off before we even knew about them because they did not provide a competitive advantage.
Something to think about for all the people who think everyone getting infected with a milder virus will end this. Every infection presents a mutation risk. Not just serious infections. Infecting a billion or more people with a mild virus conveys immunity to all, which has benefits, but it doesn’t stop the chance for mutation. It increases it. If Omicron originated via reverse zoonosis as is a plausible option, it’s theoretically possible some Delta descended mutation is stewing in another animal reservoir which might be more competitive than this, so even if no human mutation occurs future mutations still might. Which results in more rounds of “is immunity holding up?” If the answer stays yes, then some authority will declare Covid endemic and we go on. But with the underlying knowledge that mutation potential still exists to change it and we could get a bad Covid season or epidemic.
As to your first point, comparison to bacteria. It’s like I said before. The natural selection process is against *immunity* not vax vs no vax. Vaccines aren’t providing a different enough environment than natural infection. Strong response vs weak vs not at all is a question… but a virus mutation that doesn’t get destroyed by an antibody doesn’t care if your body learned to produce it via natural infection or vaccination. If you are concerned about this, then you should be working to prevent any infections from occurring which involves those things no one wants to do. This bacteria argument is in favor of zero-Covid which means serious lockdowns. You may think you are trying to make the case against vaccination but that’s not what it means.