Just realized my eyeline is too low and smushes up the face lol whoops

I would suggest that you consider varying the width of your lines regardless whether they overall are thick or thin. This goes a little into what I understand about form and it is just one approach of course: almost everything we see as „lines“ are actually cast shadows caused by creases, overlaps etc. A crease on the skin is a form change on the surface of the object. Without going into too much detail, those creases are not suddenly sticking out of the skin at a 90 degree angle but rather they start small, get deeper/higher and then fade back into a surface. The shadows they cast do the same. So by drawing a line thinner on one side, thicker in the middle and the thinner at the end again, we indicate that behaviour. This gets way more complicated the more you think about it and the more you consider (like the form the shadow is cast upon is actually distorting it. In the case of the rhino, the rounded body, the position of the light, the size of the wrinkles/creases/forms we see all affect the line width and when any of these parameter changes, like a bent surface that changes the direction it faces, the line weight changes as well, etc.). Honestly it drove me insane when I got to the exercise covering this topic over at drawabox (lesson 2, texture exercise) and I have certainly not mastered it, so I won‘t go into details here. Bottom line: having your lines always be one consistent width can look constructed and mathematical. Changing the line width often looks more natural especially on organic things. (And as I said: just the way I think about it). Depending on what you are going for I am sure there are also styles that can pull of line weights that are consistent throughout