What exactly did the covid vaccine do? Why was it better to get it?

The majority of people beleive covid is not dangerous in an average health person but is dangerous to immune compromised, diabetic, someone with lung or heart issues, etc.

Alot of people didn't get vaccinated because they thought covid would kill them but wanted to get it to protect others. How exactly did it protect others? There is no data anywhere that indicates it prevented you from infection and there's also no data that if infected you could not spread it to someone else.

Tons of people caught covid and had no symptoms what so ever during the entire infection and tons of other people were infectious for multiple days prior to symptoms. The vaccine in no way prevented you from spreading it to anyone else.

The vaccine lessens symptoms though right? What is the evidence of that? If we already know people regardless of vaccination status got either minor colds, extremely sick, asymptomatic for the entire course of covid, or died all REGARDLESS of vaccination status how can we say " it lessens symptoms".

My personal unvaccinated covid experience was not symptoms what so ever except loss of taste and smell for a week. Both siblings were vaccinated and my brother in particular is much more healthy than me and was in his last years in the army. I'm an overweight smoker. My sister has an immune compromised disorder which is why she wanted to get the vaccine. Both my brother and sister were hospitalized when they caught covid.

How can you say " the symptoms would be less severe". 1 person you wouldn't expect to get a serious case did. 1 persons you expect to get a serious case did and 1 person unvaccinated who SHOULD have got a serious case did not. All the exact same genetics. How can you say "oh if your sister didn't get it she would have died for sure". If she died would they say " she would be less dead"?

It's just a phrase they kept saying because there is absolutely no way to actually prove how much or how little the vaccine contributed. The control would be the unvaccinated, and yet some absolute fanatics will read this and not even beleive I didn't get sick and don't beleive the thousands of people who also didn't get sick regardless of status.

So if it Cleary doesn't prevent catching, spreading, or death what the hell does it do? And how good is it at doing that? 90%? 80%? 50%? What success rate would it take for you to say " oh it was pointless"?