For a first game, this is pretty good. It has some interesting ideas like the shop and taking damage making you lose time. And, of course, being able to pet the dog.
The fun does get dragged down a bit by the slow and floaty player and not really explaining mechanics like being able to jump when you walk off a ledge, or taking damage losing you time. It's also unsatisfying to bonk your head on the upper platforms which is why a lot of platformer games have their ceilings higher to avoid that.
I'm also confused as to why you would ever pick the dash over the double jump since the level is mostly vertical and the double jump makes you go up even faster. If it were two different ways of going upwards that control very differently it would be a much more interesting decision to make.
Overall, though, I think this has some potential if you polish it up a lot. Great job!