I am going to try a slightly simplified explanation here, not because I think you're stupid (I absolutely do not think this) but because it may help explain how this works. If it feels like I'm stating the obvious at any point, I apologize; I'm trying to walk you (and anyone else reading this) through the steps one at a time.
When you're sick with a virus, you shed live copies of that virus. For some infections, it comes out in your poop or your blood or whatever. For others, like Covid, it comes out in respiratory droplets (mostly when you cough, sneeze or spit). Speaking, singing and shouting can also spread these particles, however.
Some viruses are pretty tough to catch, either because they die quickly or because they have to follow a certain route to get into your body. Some viruses, however, often those which spread via respiratory droplets, can sometimes be really, really easy to catch.
Generally speaking, the sicker you are, the heavier your symptoms are, and the more you will shed viral particles that can infect other people. If you have no symptoms, you can still shed viral particles though; my understanding is that asymptomatic people generally tend to shed less, but they also might be less careful as well, leading to more transmission by accident.
When you get sick with something, your body tries to fight it off. In doing so, it creates antibodies, which are like a specialized task force intent on protecting you from a specific infection.
The problem with Covid-19 is that until two years ago or thereabouts, we've never really seen a disease like this, so we don't have Covid antibodies floating around in our system the way we do for other, more common viruses. Humans are really used to things like cold and flu, because even though both diseases can mutate, neither seems to do so in a way that freaks out our immune system. Our immune systems are sort of always on guard for cold and flu, so when it detects them it fights them off. The bigger the dose we receive, the harder it is to fight off.
However, Covid doesn't enjoy this status. Our body takes a bit longer to recognize that the thing that's suddenly invading it is, in fact, hostile. The body will still trigger this immune response on its own (this is why some unvaccinated people can get better without any help), but the slower response time, and the fairly unique qualities of Covid-19, make this a bit dangerous.
What the vaccine does is essentially give our bodies a memo that tells it what to expect, giving it an early warning system. It doesn't infect us with live, crippled virus, the way some vaccines do. Instead, it tells our immune system to be on guard for specific sorts of proteins which signal a Covid-19 infection, which speeds up and strengthens the immune response.
As time passes, humankind in general will become more used to Covid-19, and herd immunity (i.e., the point where most people have antibodies floating around, either from vaccines or from at least one prior infection) will occur. The reason that we needed vaccines in the first place was because the mortality rate of Covid-19, while not super scary, was still considerably higher than other comparable viruses floating around. If we had left this alone and just sort of let it run its natural course, millions more would have died.
It's also important to point out here that viruses tend to mutate most readily the longer they exist while under attack. A weak immune response (i.e., a person gets sick and is taking awhile to get well) offers the best chance of viral mutation, and here again we come back to vaccinated people. They usually have a stronger immune response, so they give the virus a shorter window in which it can mutate. Mutations occur all the time, and most of them are completely harmless and pointless. However, the reason we keep seeing new variants is because this virus is still infecting enough people for enough time that eventually it was going to throw a mutation that was an improvement (from the virus's point of view) over its last iteration.
So let's summarize.
1. When you get sick with a virus, you shed that virus for awhile. You can make other people sick. This is how viruses flourish in the first place. The less protected you are (either through natural immunity or through vaccination of some kind), the more viral particles you'll shed. Wearing a mask blocks some of these particles from spreading to the environment around you, but it's not perfect. Same goes for physical distancing.
2. If you have antibodies in your system, you will generally fight the virus better, which means you'll get better more quickly and will shed fewer particles for others to potentially catch. It also means that you're providing the virus a shorter window in which it might mutate into something more dangerous.
3. The Covid-19 vaccine teaches our immune system to create some antibodies specific to this virus without actually giving us the virus itself. These are antibodies we would not have had without catching the virus otherwise. Unlike cold and flu, they aren't already in your body. Your body has to recognize a threat before it knows how to deal with it.
4. Since the virus itself is far more likely to kill a person than the vaccine will, and since both catching Covid and getting vaccinated provide similar protection, it's generally believed in most reputable scientific circles that getting vaccinated is the safer option.
5. Being vaccinated not only means that your own immune system is better prepared to protect you, it also means that you, as a carrier, are less likely to pass infective viral particles to other people.
All that being said, I do want to point out that Omicron is a mutation that has managed to be considerably more contagious than other forms. If vaccine efficacy was at, say, 93-95% for Delta and other earlier variants, it's closer to 75-80% for Omicron. that's the nature of viruses like this though, unfortunately. Scientists are hopeful that Omicron is an endpoint, since the virus actually doesn't do best if it kills you quickly or horribly. It does best by being communicable, and that's where Omicron is at (higher transmission, lower symptoms overall).
Do you still have questions? I hope I've explained this to your satisfaction.
Check out my Manamon text walkthrough at the following link:
https://www.dropbox.com/s/z8ls3rc3f4mkb … n.txt?dl=1