Certain aspects of an organism evolve very quickly, others very slowly. 4-5 million years is not enough time for all of these changes.
Things that can happen in that time frame would include:
Developing quadrupedal locomotion: Environmental factors that favor speed over manual dexterity could easily make this happen. A human will probably not get to feline like speeds in such a short amount of time, but perhaps something more akin to bear or elephant locomotion is doable. Since both can top out at ~40km/h, this is plausible.
Growing to a large size: 12-15 feet is about the maximum size for a mammal, but it might be doable with strong enough of environmental factors, that said, animals that big tend to struggle with top speeds.
Lose their fur: No mammal has ever truly lost all of its fur/hair, but it could become mostly hairless like a whale or a homosapien.
Develop a crest on the head: This could be the result of a single mutation, but for it to spread through the population, it will need to serve some aspect of survival such as acting as a form of natural armor to help protect the brain, or to increase surface area for stronger jaw muscles.
Mostly blind but have some sort of extrasensory perception This is a common evolutionary feature of creatures that live in caves or at ocean depths greater than 150m. Animals that evolve in these circumstances often become albino which would make them sun sensitive.
It is very unlikely that you would see this feature evolve alongside many of the other features:
- If your proto-human is cave dwelling, then it will benefit more from bipedal locomotion and smaller size so it can continue to use its hands for climbing and be able to fit through narrow spaces.
- If it became aquatic, it would still need to spend enough time near the surface to get air; so, it probably would not lose its eyesight. It would also begin to look like a sea lion or dolphin meaning it would not become quadrupedal, and certanly could not do 40kph on land.
That said, many mammals already have the potential for echolocation, but only a few species do it instinctively.
Things that can not likely happen in that time frame would include:
Squid-like body type/tentacles/smooth exoskeleton: This would take more like 500 million years. Primates are vertebrates, and you are asking about invertebrate features. Endoskeletons and Exoskeletons are two completely different solutions that nature found to the same no-skeleton problem. Once an evolutionary chain has solved that problem, it's not going to go back on 500 million years of success to start experimenting with a completely new solution when it has one that already works. It would simply take too many generations of being disadvantaged by intermediate features for evolution to cross that gap.
Best Case Solution: Convergent Evolution
In nature, there is a thing called convergent evolution which is where two unrelated creatures evolve to have similar features. One solution to this problem is to have an Octopus evolve to have human like features. It's genome already has many of these adaptations. An amphibious octopus may have evolved a sturdy exoskeleton to help it stand outside of water. Over time, its need to outrun terrestrial predators cause some of its tentacles to fuse into fewer and stronger appendages so it can run faster. Still being slower than most predators, it turns to the trees to live like a monkey. Here they develop whatever monkey/human like features you want them to have from evolving under the same niche. It can begin forming language, tool using, whatever. It may retain under developed eyesight from its ancestry of being a deep sea creature, it just never got better because it's always solved that problem with echolocation. Over time, it's natural forest environment begins to disappear and it needs to adapt to life on the ground. From here evolution pushes for a bigger and bigger body to make sure that it is too big for predators (much like an elephant.) In the end, you get the creature you are looking for, but it just didn't evolve from proto-humans at all.