Fur combined with skin oils is a great insulator as it is a hydrophobic surface in which air bubbles get trapped proving very good insulation.
Our skin is very porous and thin and gets soggy very quickly in water which makes it less grippy and weakens it.
We also have terrible physique for swimming (hence why we need to develop complex swimming techniques instead of just paddling) just to put it into perspective a deer can swim as fast as 15 mph, a polar bear can swim at about 7 mph for 10 hours the fastest human swimmer can swim at around 5mph and that’s for a 100m sprint, we have fairly poor buoyancy and a very weak diving reflex compared to other mammals and like most apes we are actually quite terrified of water naturally.
Our vision is also severely impacted by water, especially salt water and we have a very water ingress unfriendly nose-ear system.
The whole aquatic ape theory doesn’t make any sense it’s almost as crazy as the chimp fucked a pig theory.
Like seriously take pretty much any other non ape mammal and you’ll discover that they are so much better at swimming than humans that they might as well be fish compared to us even those who don’t look like they should be able to swim at all.
Like freaking mice have been observed swimming for 3 days straight.
I also like the idea that consuming fish and shellfish contributed to our brain transformation, given omega 3 is highly beneficial for healthy brains.
Shellfish have pretty much no omega 3 in them, cold water fish do which are hardly easy to catch in shallow waters.
Nuts and seed however are much richer in Omega 3 than most fish.
Again the aquatic ape theory does not stand up to any level of scrutiny pretty much any claim it makes can be disproven or attributed to other much likely factors it is pseudoscience in its purest form.
The truth is that AAH doesn't match the fossil record (or the fact that apes have been observed swimming even in the wild since it was proposed, the fact that in captivity apes develop similar or higher subcutaneous fat deposits to modern humans, and the average ape still has a higher body fat percentage than a human athlete).
Australopithecus afarensis (Lucy) circa 3.5Ma was bipedal, Australopithecus anamensis 4.2 Ma was bipedal as well albeit with primitive features for the upper body, Ardipithecus ramidus which is about 4.5 Ma had both habitual tree and bipedal adaptations (e.g. could stand upright and likely walk pretty well but had opposable big toes for grabbing at branches).
The earliest clear signs of modern bipedalism (as in a walking gait similar to that of modern humans) is around 3.7 Ma and it's not a skeleton but rather the Laetoli Footprints in Tanzania.
For the most part we had direct and "in-direct" ancestors for about 5 million years with varying degree of bipedalism, we likely haven't been eating seafood at for more than 200-300,000 based on remains found at various sites.
Lastly Shellfish which would be the easiest food source for the shallow water Aquatic Ape is one of the most common food allergies with 3-4% of the population suffering from it, and it causes Anaphylaxis in almost every case unlike other allergies which vary in severity. If we count in seafood allergy in general which includes finned fish then about 2.5% of the adult population suffers from it.
It's quite unlikely that a common food source that impacted our evolutionary path so greatly would have a fairly deadly allergy tied to it.
On the other hand humans are not allergic to mammalian meat (unless they are bitten by a few species of a tick and develop and Alpha-gal allergy) at all, and only in extremely rare cases are allergic to poultry.
I've seen numerous speculation on the finger wrinkles, possibly an adaption.... or possibly just happenstance. Sure today's fingers prune significantly, not sure they would do the same if heavily callused by a decade or two of hunter gathering for all your food. In any case it's not unique to humans, macaques have similar and I suspect it's noticed because they bathe. Couldn't find any information on other primates.
[edit for minor spelling/grammar tweaks]
The bulk of our hair is on the top of the head - the only place that would be burnt by the sun if you stay all day standing in shallow waters.
The shape of our nose (nostrils directed down) are made convenient to stand vertically without getting water into airways.
What is the picture of a paradise? A beach with a white sand, sun shining, clear blue water, lots of palm trees near the coast. This is because its our natural habitat. Not deep forests, not savannah. It's tropical beach!
If I was to be left alone and naked on an inhabited piece of land I would definitely choose a tropical beach out of all untouched locations on the planet, because it is the most likely place where I would be able to survive.
It's fun to think of the ramifications though. Are/can we look for human fossils in the right places? How much of our history is potentially under water and not African caves. Did it help spur fire usage so that we could safely eat fish? Did it influence the out of Africa migration which was mostly coastal (we got to Australia before Europe)?
It probably didn't affect our evolution much but I suspect a lot more of our pre-history was spent at least on the shallow ocean than we have evidence for.
BTW Apparently out of favour, but I like the aquatic ape theory too. Shellfish are high protein, support brain development; coastal settlements found.