I realized something about Helena's songs. It turns out they're not obscure French nursery rhymes that I'd have to spend hours researching. She makes them up!
We've been playing with her shape-sorting castle. Helena embarked on an elaborate dance-like pattern with all the characters — king, queen, court jester, and squire (well, he looks like he should be a squire) — exiting through the drawbridge, leaping from turret to turret, then plummeting to the floor.
And all the while, she sang! The lyrics were mostly gobbledygook (or possibly French), but the words "castle," "king," "queen," and "tombé" were clearly intelligible. Steady rhythm and a recurring musical motif constructed around these particular four characters.
There are other games and other patterns, with other songs. She makes them up!
A jazzy Aristocats-inspired "oh yeah" finishes off many of her tunes.
Helena's musical appreciation and competence has risen to such a level that she now sings along with us in the car to Blur's Song 2. Woo hoo!