My guess to why the ads are so different:
The firms making the ads are probably completely separate from the developers. Could be just random people from fiverr making the ads. They get barely any gameplay footage, so they just come up with some random gameplay that looks fun in an ad.
I guess the game developers might be some random people from fiverr as well.
As to why it works: no idea. I guess some people just donβt care, and given how cheap these games are to make they probably just need a few people to break even.