I think value and contrast go hand in hand tbh. Like, you can't add color values without contrasting something (even if it's just a teensy bit), and you can't make two things contrast without changing at least one value, y'know? It's like if you put pink and purple in the same picture, but left them at the same value; they wouldn't contrast. If you set the pink to be a little more dull though, then they both stand out a little more.

Shape plays a big part in it too but don't even sweat it you've got shape down to 👌👌👌.
And also that boy be fokin rad.

Hue plays a big part in the value of colors too, and then I get even more confused

Well, take a look at his pecs and abs. Literally the only difference between the two is the amount of shine. The hues are the same, but the pecs have more value to them because of the whiter parts bringing the light, peachy color out. The abs have less value because of the shade from the arm, so they don't come out as much, but it brings your attention from least to greatest, or in this case, from the abs to the pecs, and then the face with the contrast with bone yellow and hot pink.

You can also put it like this, Value is literally just how much of a difference in "pop" that your hues are making. If it looks more saturated, then it has positive value. If it looks more grayed-out or dull, then it has negative value, but negative value isn't a bad thing. Looking at the bubble o' goop, you did the opposite. You have more value at the bottom, but less at the top, which brings your attention from the top to the bottom, just like how it's pouring. Just think of Value as the direction that your eyes go in when you look at something. I feel like that would make it a little easier. You really do have that down already, though. You did it up there twice. uwu