Russia wanted to place nukes on Cuba, the US said ‘if you do this there will be war’ so Russia backed down. This did not lead to an all out invasion of Russia, this lead to a de escalation and Billions of people not dying.

It is a little more complex than this.
US deployed Jupiter nuclear missiles in Italy and Turkey and URSS, to retaliate, deployed R-12 and R-14 ballistic missiles to Cuba. And before taking any action, US denied the deployment of URSS missiles.
When US aknowledged it, the first option suggested to Kennedy was a air strike on Cuba and an invasion.
What happened is that US put in place what was basically a naval blockade of Cuba (even if they call quarantine to avoid war related terms) and then started to talk.
The end result was that officially URSS retired the missiles and bombers from Cuba, and US agree to non invade Cuba and secretly retired the missiles deployed in Turkey (not sure about Italy).

But I am sure that you understand that this worked exactly because the "if you do this there will be war" was a credible threat ans was sustained by actions (the blockade)

Now, in Ukraine if you propose a cease fire what actually can put on the table to make Russia back down from the invasion ? A deal which will be ignored in [choose your number] years ? Let Russia keep what they gained and go without repercussions so they can pull the trick again in [choose your number] years ? Do you really think that Ukraine would accept to lose part of their terrirories (which btw are the ones witn more resources like gas and oil) ?

I agree with you, we should find a way to stop the war. I simply don't see how being accommodating with Russia will make it when the root cause of this war is that we let Russia think that they can do whatever they want without any consequences.

I gave you my honest answer, let me ask you a question in return. Why are you not volunteering? Ukraine has a man power problem because even the Ukrainians don’t want to die for this cause. So if it’s so important, why don’t you go there and stand on a Russian landmine so a Ukrainian conscript doesn’t have to.

I am too old and no more phisically fit.