My original answer pointed out.
God invented the concept of marriage Adam/Eve was the first human marriage.
Sexual relations are forbidden outside of marriage whatever that entails.
There are no translations of the bible where this has explicitly changed.
Then a poster asked why the bible forbids same-sex relations. I said it was to do with.
The sanctity of marriage.
Populating the planet.
The family unit has many functions one of which is to provide sustenance/home etc for any offspring.
The idea we can replace the duty to parent with a paternity test is absurd and we know in today's society is troublesome, we also know the government via the tax system providing sustenance for families is not sustainable.
Then I personally speculated the population of the planet would be under threat with a small or significant shift towards same-sex relationships.
To answer your first point animals are not under any commands from the bible. The Bible was written for humans.
Then God said, “Let us make man in our image, after our likeness. And let them have dominion over the fish of the sea and over the birds of the heavens and over the livestock and over all the earth and over every creeping thing that creeps on the earth.”
As for modernity, the 10 commandments are still relevant. What people don't like is the idea of a GOD via the bible and religion setting out objective rules.
This leads to all kinds of wonderful sophistry to either deny or mock.
I'm not bothered, posters are not mocking me, they're mocking what is written.
It's interesting that academics can debate these topics with wisdom and piety, yet the internet can not.