See my reply 25 - my notes are almost verbatim re a prior exchange between Freepers jonrick46 and ifinnegan; my notes being my attempt to make their explanations easier for me to read. They get all the credit; any errors are my problem.
I think that reading into it, it partially answers my questions, assuming I understood correctly. If you've had and recovered from Covid, your body's immune system could react to a future infection via at least two different paths (reacting to the spike protein or ribosomes). If you've had the vaccine, the immune response would only come from the spike protein.
To me, that still seems like people who have recovered from COVID wouldn't benefit from the vaccine, and people who've only had the spike protein vaccine would only be protected against variants of Covid that had spike proteins that your body's immune system recognized.
I still don't see how the vaccine could be longer lasting than natural immunity (I get the idea of dosing, the vaccine gives a significant dose over two instances, and some people didn't get significant cases where their bodies really registered a big response) but this is assuming you got the disease, your body learned how to fight it off, and recovered.
To me, it all seems like it's a matter of of pleasantly filled out spreadsheets being the measure of success in battling the disease, not a function of how few people end up in the hospital because of it.