> Why did they never find time to learn to build complex homes? Why did  never
> they find time to learn to paint beautiful masterpieces on canvas? In  short,
> why were primitive people so stuck on remaining PRIMITIVE?

Gordon,

The reason HGs did not learn to write, build monuments or complex homes,
symphonies, etc. is because EVERYONE in the tribe was expected to obtain
food for themselves as well as the tribe.  Moreover, the tribe had to move
from place to place to find an abundant hunting/gathering area when another
area was becoming depleted.  They usually returned to familiar spots after
the wildlife had completely restored itself.

The reason neolithic man was able to develop so many cultural "advancements"
over HGs is that the work of producing food was the responsibility of a
relatively few and the population remained in one permanent settelment
(i.e., was not nomadic in any way).  Other people had time to think about
mathematics, science, architecture, engineering, art, etc.  Not everyone was
involved in producing food.  For those that did produce food, life was very,
very hard.  If you haven't, read "Guns, Germs, and Steel" by Jared Diamond.
It will shed much more light on this subject, while not deifying HGs.