I laughed heartily, but it also had another effect: I thought that modern children rarely have the opportunity to witness the union of man and woman and that they learn everything to do with sex in theory first.

Children today have way more access to sexual content than we ever did as kids, thanks to computers. We're innocent babes compared to what your typical teenager can access online. As you said,

Since people want to witness other peoples sex activities and rituals, they shifted this need to the world of the screen.

Porn and prostitution is a phenomena and from what I think, an expression of what can go wrong when humans suppress their biology.

I'm not so sure. It appears that prostitution (or similar behavior) also exists in non-human animals (Wikipedia). If this behavior persists in animal populations, then it must have an evolutionary advantage. Porn is a more recent development (evolutionarily speaking), though we've been painting sex scenes for a long time. Animals also enjoy watching porn of their own species, though I have yet to hear of animals making sex videos in the wild 🤣