How do you describe songs like Little Apple, Most Dazzling National Wind, etc. in short words?

It can only be described as a "brainwashing song". Anyone with a little bit of music knowledge will see that the repetitive melody of "3126 32126" "3122 53711" in the chorus part of Little Apple is accompanied by super popular and rhyming lyrics, and the narrowness of the range of the sound does not have any difficulty in undulating, so the general public can sing it in a catchy way. It's so narrow in range that it's catchy enough for the masses to sing. The earworm effect is no surprise with such a continuous barrage of hits. No matter how much you don't appreciate the retarded lyrics, the body is still honest.