Consider how animals like cows behave and think. They have a sense of survival but their deduction and reasoning isnt like humans. Hooved animals will not walk over some terrains. Horizontal depressions in a drive or road can be enough to keep deer and other animals from crossing. Its unsure footing and ****s with them so they try to avoid it. And animals do counter intuitive stuff all the time that results in death and could have been avoided.
Sure we think, "Jump in the water, Mr. Brachiosaur!", but this is a giant 62 ton herbivore that may never have been in the ocean or have any instinct to jump or walk into the ocean. It doesnt know what the fire is, it doesnt know that water can maybe save it, it doesnt know what's in that water and how deep it is, or what to do. Its surrounded by fire, lava, smoke and ocean. The only thing on its mind is crippling fear and potentially deadly obstacles all around it. Not to be cruel but in a situation like that it's almost too stupid to survive on it's own, and that makes it even more sad. It couldnt save itself, but humans could have.