Is the human body structure best suited to their intelligent brain?
In other words, could there be any kind of other body structure that could have helped even more the intelligent brain we have. Of course taking into the Aesthetics too.
The only way that can evolve is through tools and social cohesion. For a small mammal to evolve to tackle on bigger game and thus more efficient protein sources, it either needs these things or adapt its body. Unfortunately, adapting your body is expensive as well. The only positive feedback loop is through tools and social behavior.
Wolves are intelligent animals as well. Probably as smart as toddlers. They are very social creatures that take on much bigger game. But they don't have hands.
From using tools, primates were able to streamline their body mass and reduce apparatus needed to digest vegetation. Thus, from the point of view of efficiency, I think the human body is very optimized for an intelligent brain.
It's not the only way it can happen, but it's very probable (at least to evolve from existing animals).
They lay on the couch while I'm working to produce what can be transformed into protein for them. It's a pretty efficient and pretty safe strategy evolved in a few tens of thousands of years.
There was a comedic bit about dogs in New York City: If an alien saw two creatures of a different species and one was picking up the other's poop, which would it deduce was in charge?
The great-chain-of-being is the product of revelation not scientific method.
We can turn the ontological argument on its head. I can conceive of an omniscient and omnipotent intelligence, therefore human intelligence is very low on the absolute scale of intelligence and calling it intelligent may be misleading.
Going further, the question "How is a human with a different sort of body still a human?" hints at an assumption of mind-body dualism. Radical Skepticism aside, is a disembodied brain still a human?
I guess Aesthetics with a capital \#a were thrown into the mix to make the question less trivial?
When seen on a biochemical level, evolution creates highly optimized stuff on "hardware" as well as "software" level. (Also, it is quite telling that it is often impossible to distinguish between those.)
When interpreting this as hardware/circuit/software design, the "code" produced by evolution is by far not the cleanest or nicest or best understandable. It is more the kind of code that you see in mature projects, decades old, where the simple algorithms have been optimized more and more, making them harder to undestand, but still correct, robust and with better performance.
Interestingly, even the best engineers need lots of trial and error to finally come up with these algorithms. Maybe their optimization is more targeted than evolution's, but engineers also have almost no time for their experiments (when seen on the scale of evolution's time.)