surely? humans have evolved to witness and learn about the sex act from birth onwards?

Question

i often wonder if there would be less screwed up people if this were so.
that is how u would learn about it 10,000 years ago if u lived in a cave
instead of discovering it accidentally , with accompanying embarrassment or from immature peers or exotic pornography
all (nearly) parents hide the act and whisper about it

Answer 1

We have a screwy culture which has taught us the human body is shameful and sex is not allowed. A lot of it in the US is a holdover from the days of the Puritans, who believed sex was a sin; but much of it is also an attempt to protect the innocent people (children) from those who would show them things before they are prepared to know. (predators).

Answer 2

You have it exactly backwards. All human cultures have sex in more or less privacy, for the most part. Swinging is a Western " thing ", that is not all that prevalent. Even baboons go into the bushes. We are evolved more toward the private act of sex, so please spare us any over reaching social engineering projects you were contemplating.