I think you should lengthen the cooldown of Infection if you work on it more, as you have said in other comments.
Many games now try to keep most buttons near-ish to the WASD keys as it means you can play them with one hand! But it is only a suggestion. I would recommend testing W to jump and Space to attack. I think it would feel very natural.
Personally, I'd like to see more games just allow movement to be both on WASD and arrow keys, meaning you can switch and swap at any time (keyboard games can feel cramped after a while) and make it easier for left or right-handed people, but that is just me.
Perhaps the enemies could knock you quite far back? I notice now that the blob enemies both shoot and hit you with.. their tongue? The amount their projectiles knock you back could be a universal knock-back. Meaning the player does not want to get hit. The player knocking back the enemies quite far when hitting them could be a fun addition.
No issue at all with the precision platform areas themselves! But I think you should choose. If you prefer the floaty controls, then the precision areas should go. If you liked the precision areas, the floaty controls should go. Personally, I love pixel art games and many do not have floaty movement, so I would just remove the floaty movement and keep the precision areas myself...
Good work, once again and look forward to seeing more!