I really like this idea ! That is actually fun to play.
However I see a few improvements I'd love to see you make to the game : make the character faster + 2 tiles-high jump, but to counter this removal of constraints, make the Tetris blocks already falling before you press J manually, I think it will make the game faster and more fun.
Also of course, adding music would be really nice, as well as mabye some variations with additional mechanics, mabye falling bombs for example.
Anyway good job, I'll be happy to play it again if you update it !