I was a big fan of Insaniquarium growing up! I think this was a unique take on the formula with some cool artwork and ideas thrown in. The auto-feeding mechanic was interesting and I liked it, but one of the frustrations with Insaniquarium that I think you could address in this game is that the player spends a lot of time with the mouse at the bottom of the screen collecting coins, but the player also has to feed the cells from the top of the screen so they can float down before disappearing. I found that the switching from top to bottom was a little more frustrating than fun, and thought it could be cool if the lungs would spawn oxygen from the top of the screen instead of at the mouse, as if the oxygen is being absorbed into the bloodstream!
I feel like you can work with the unique setting to further differentiate this game from Insaniquarium a bit more too, for instance, what if food/coins fell sideways instead of down? As if floating though the bloodstream perhaps?
Anyways, a cool little demo nonetheless! You introduce some neat little spins on the Insaniquarium loop. The art is cool too! I do think you can do more to make this game more unique, however! I look forward to seeing how it comes together.