I think the concept of an ideal may be flawed. What is ideal changes based on what the current situation is.
That goes for the ideal human body as well as the ideal human philosophy. We need to evolve constantly to fit with our current situation.
People get fat because famines killed people a lot. People have sickle cell anemia because sickle cell traits protect against malaria which killed people a lot. A lot of cancers are caused by mechanisms that protect against things that kill people a lot. Different personality traits that look suboptimal exist because those strategies were successful over time. Yeah these traits look bad when that situation doesn't exist, but they're much more likely to help in the aggregate than to hurt particularly with stuff like cancers which tend to kick in after an individual has reproduced so don't have as much of an evolutionary impact.
A lot of the same goes for philosophies -- people tend to follow what works, and what works at one time doesn't work all the time -- ask gen z as they're given advice by boomers.
All this is one good reason to be wary of genetic engineering. We'll get rid of all the "bad traits" and be wiped out because some of them were there for good reasons we don't understand.
The knee needs a complete remodel as well. The whole thing reeks of reappropriating an old 4-leg design for a 2- leg model, and that’s just never going to work well.
A theoretical perfect human would never have a disease or illness and have perfect control of their thoughts, emotions, and actions. Humans would not be born missing limbs or with extras, or with things like missing or extra chromosomes. Basically, the DNA (which would be undamaged and free of genetic anomalies) in humans would be followed perfectly by the human body.
I would even say the theoretical "perfect human" would never age beyond maturity or die of old age. Scientific observation shows the human body has built-in functions to account for this, as all cells in your skin are replaced every 7 years for example, but for some unexplained reason, things start to go wrong which is part of what we call aging. Science still has not exactly determined the cause. One theory is cumulative cellular or DNA damage caused by various factors over time like stress or radiation and such. Another theory is that DNA has a pre-programmed life-span. Neither of these have any definitive scientific proof or evidence at the present time, though theories often fluctuate as more evidence is uncovered, so these may change in the future.
As to the appearance of this perfect human body, it would very much look like young healthy humans we see today. There is great variety contained in the human genome, and none of these varieties would be considered any better or worse than others. Skin tones, eye and hair color, height and weight, even intelligence levels, are all factors that can vary greatly in human DNA.
Actual answer, there clearly isn't one ideal body type and that's good for the species. I like the show Physical 100 because it does a good job showing that.
Personal answer: imagine the peak performance of humanity if balls weren't on the outside!