Yes I understand what you mean, to have a common look for all the art. I am working with one and the same artist on the enemies, but for the tiles I have not been able to find one artist who do it all.
From the old video you posted, I suggest you work also on visual feedback details. Like knockbacks, screenshakes, maybe make it more fast, rather than it being like early Metroid slow paced. From new game standards games tend to be faster. With a bit more flow and some simple story idea. Maybe some new mechanics that could be used for level progression like the roll POWER, just something new you have to get to progress deeper. More level branching leading to some dead ends maybe and some collectables for some sort of reward.