Don't have time to read al the answers, but I will be back for the wisdom - this is my troublesome subject, or at least was. I was terrified of the moment when I'd tell my son that my mum had passed away (almost 18 yrs ago) as he is also very intelligent and simple answers won't do, so I had no idea if he'd make a connection that if someone's mum die, perhaps his can too...
In the end he actually took it rather calmly, as a fact of life, something I had tried to portray that way... we often start by simple picture of the world, then build up on it... "people die when they are old...(insert name of the people he knows about here)" then, some weeks or months later "people die when they are old or when they are very very sick". Now we're at the stage "people die when they are old, or when they are sick or sometimes accidents happen". I always tell the truth, although a bit simplified to begin with.
Also, "When some people die, some other are sad", then next time I add "and although they are sad and some may cry, it is important to also remember how much they loved each other..." I can see he digests it, some thins will of course only make sense later, but I think the fact I make no hype over death has some effect. TBH, I sometimes fake calmness big time, I am not so terrified of death as I am of not seeing him grow up.
Which is why I use every opportunity to plant into his head that I love him and will always take care of him, wherever he or I may be. For me the reassurance is the key to offset any (potentially) troubling emotions now that he is still so young and sees the world b&w.
He even had a stage just weeks ago when he wanted to play "let's be dead", to which I just reacted calmly, the same way as if he wanted to play tickle monster... like to most normal thing, do what he wants once, no fuss over it, get it out of the system a bit and next time try to suggest some other 'game'. Some family members once heard that request and over-reacted a bit "oh dear, that's not the game you play", but I stepped in and played with him (spooky, I know).
He asked me when I'd die, but I know it was just his curiosity And I said the truth "I don't know, nobody really knows when they'll die" and then the distraction/life lesson technique, "but that really does not matter, what's important is that we are here now and we love each other".
Have you tried watching "The Lion King" together? I know some parents use that as a story to introduce the whole concept of death, where the circle of life seems to help a lot. We only ever watched it once and he doesn't want again, but no so much because of Simba's dad, which is what I suspected might be the issue, but because he doesn't like the evil Scar. I think for my boy the concept of evil is a lot harder to digest than death.
I hope this makes some sense and you can reuse some ideas. Will be back to read everything, thanks for starting the thread!
