The human powered aspect is
nonsense the point of the exercise.
Corvallis, OR, has their Da Vinci Days race each year.
https://www.davincidays.org/
The best entry I saw personally was in 2014 or so (last time I went). It was a yellow plastic septic tank on six go-cart wheels, with four or five occupants and a boom box playing their cover of 'Yellow Submarine'.
More common is the single-occupant canoe on bicycle wheels.
edit:
Next thing I did was go to JACG, and find this:
justacarguy.blogspot.com/2024/04/the-drag-stripper-that-specialized-has.html