This is a good question, and there are actually some scientific issues to consider. I think morally we can all agree that it would be wrong to kill someone to eat them. But let's consider the situation where you're starving, and someone has just died in front of you due to no fault of your own. Is it "safe" to eat them? Will it benefit you?
The first issue to consider is that most disease organisms are specific to the species they infect, or at least have a high affinity to a small number of species. Therefore the more related you are to the dead animal, the more likely you are to pick up a disease from it. Of course there are general pathogens too, so cooking the meat is always a good idea. However, with something that can host the same diseases and parasites you can, like another human, the danger is even higher. You really really want to cook the meat.
Another less obvious issue is what parts to eat. Some organs contain high concentrations of hormones that can disrupt our normal processes if taken into the body as a whole. The exact composition of most hormones is species-specific, although they will still have similar broad affects across species. For example, insulin for use by human diabetics used to be harvested from pigs. On the large tree of life here on earth, humans and pigs are quite close, so it worked, although probably not quite as well as true human insulin.
In particular, avoid glands like the pituitary and thyroid. Such parts are even carefully not included in beef for human consumption, for example. Eating human thyroids would likely be even worse than eating cow thyroids.
I would definitely avoid central nervous system parts, like the brain and spine. The chances are rare of the dead human in front of you carrying a prion disease, but this is where the prions we know about apparently concentrate. Note that prions are not destroyed by cooking, so you can't make prion-infested tissue safe for consumption in the back country.
This may sound far fetched, and it is, but it has happened. Look up a disease called kuru. Some time apparently in the 1800s at least on person in Papua New Guinea got infected by a particular prion. Due to the cannibalistic customs in that area, his flesh was eaten, more people were infected, their flesh eaten, etc, until kuru was a serious problem by the min 1900s. Once cannibalism in that area stopped, no new cases of kuru occurred.
Of course if you're starving, you're facing death by other means too, so it's a tradeoff of probabilities. What I'd probably do is eat the obvious muscle tissue, after proper cooking of course. Most of the edible flesh on the legs and arms is muscle. Unless death by starvation is imminent, I'd stay away from other parts.
