Cavetown - Rocket Ships Lyrics Meaning

For me, I guess, this song reminds me of the mentality that many people (except for this one I'll be talking about me) with suicidal thoughts tend to have.

"And it's sad but it's the truth, the world would still turn without you."

Is a direct reference to the thought that "hey, maybe I don't really matter. Because, at the end of the day, the sun would still rise, the moon would still set, and the world would still spin even if I was gone."

"But when your bones turn to earth and you ask me 'what was I worth?'
I'll simply plant a flower above you, and you can watch it grow"

This line makes me think that it's trying to inspire hope, like, yeah maybe the world would still turn without you, but you're still worth something.

I think it could either mean what I just said above, or it's someone mourning the loss of their loved one, saying that they'll plant a flower above their grave. Although they are mourning the death, they are still telling themselves that the world will still turn without whoever they just lost.

Just my opinion. :)