Animal cruelty laws are recent, as in decades. Some locales still have none on the books.
I don't believe in animal cruelty, either. But felony status for killing someone's pet is wrong. Pets mean the world to us, but as with anything treasured that is not human, our value is not what society ultimately places in it. My grandmother's letters to me are priceless, but if lost, are worth only paper.
A Google shows that in the last thirty years or so, such laws have been revised towards harsher penalties, as in felonies.
But animal cruelty laws, not so harsh, have been on the books for hundreds of years, for instance Ohio's of 1875.
I agree with most of your points.
1866 is recent? In decades? Either research your facts better, or take a math course.