We teach this song to children because it has a catchy melody and the lyrics are simple and easy to remember. In fact the lyrics are so simple that it is likely to know the song and not even know the words to it. I read them recently and realized the profound point that the song makes.

Row, Row, Row your boat
Gently down the stream.
Merrily, Merrily, Merrily, Merrily
Life is but a dream.

I won't go into some deep analysis of this song. It would seem to fight the current, after all. But I will say that, maybe instead of us teaching this to children, they are trying to teach us something by singing it.