The thing is that the deltoid should connect to the clavicle (in the front, and the top of the scapula in the back, going around the shoulder) at the side, not at the top. At the top there's bone showing up. So there should (IMHO) be a clear separation there at the collar bone.
You could see it like this too: The deltoid starts at the same height as the pecs. Not above.
Here are some references I gathered for you:
https://imgur.com/a/do23h7mAlso check out these models that you can spin around and study on Sketchfab:
https://sketchfab.com/3d-models/ecorche-male-musclenames-anatomy-33162ec759e04d2985dbbdf4ec908d66https://sketchfab.com/3d-models/anatomy2-39d4ecb5f3cd4485b534405d7714d4a3
EDIT:
Okay, my turn on drawing the muscles on top of the monster.

So, on the arm, the deltoid goes over everything. Then comes the pecs, and then the mass of the brachioradialis and extensor carpis radialis longus on top of the brachialis and biceps brachii. The brachioradialis kind of connects with the tendons of the triceps on the back, apparently...
The biceps brachii sits on top of the brachialis muscle, which acts kind of like a cushion behind the biceps. It's not just that thin stripe there (in blue).

This is the part I was talking about that, I believe, needs a better, clearer separation.
BUT... This is pixel art we're talking about here, and because of the resolution some of that may not appear.
AND... Some of what I drew is my interpretation of your own drawing.
Now that i look at it, there's something funky going on with the leg too. That muscle that comes straight down at the front of the leg, the rectus femoris doesn't go down as much as a muscle.
Here's an illustration so that I can keep on being lazy and not draw it myself (also wouldn't be as accurate):

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Here's a couple more illustrations of that:


And one of the back of the torso, because why not:
