Why would English and Scottish people call children by the term already long in use to name a baby goat?

I have been able to find no answer other than the popular guess that happy children resemble the happy baby goat. If so, why not call children kids hundreds of years earlier, especially since the Germanic root words for Child are closer to kid than child is to kid?

First, kid has only been an acceptable term for children in America for the second half of my life, which began in 1964. The slang term was relegated to the lower classes until the mid 1900s. African Americans still refuse to use the term in most cases.

Kid has been a popular moniker for criminals and prize-fighters [who were criminals in the 1800s] since the mid 1800s. Poor whites accepted the term and freed black slaves rejected it, even though their children had not been called kids in bondage.

This lower-class, white, Anglo-Saxon term for child does not make any sense unless one understands that English, Irish, Welsh and Scottish children and adults were bought and sold as chattel from approximately 1617 until the 1820s, that the entirety of the English-American slave system historians attribute to the race-based enslavement of blacks was developed largely at the expense of white children, and that the term most commonly used for the capture of children for sale [after about 1640] was kidnapping, a Scottish-English term. This term was borrowed by others sold into English and American bondage, including African American slaves. It is well known by those who study American slavery that servants of African descent identified with their masters rather than poor whites—as exemplified by such refrains as “I’d rather be a niցցer than a poor white man”—and have carried many of the traditions of the American slave-owning gentility down through the decades with them, including rampant gambling, ostentatious dress, strong aversion to the term kid, and whipping their children extensively with improvised whips and paddles such as belts and shoes.

Unable to find a scholarly discussion of the etymology of kid, I have asked a language expert to investigate this. In the meantime here are some facts:

Kid was first recorded in print in 1599, roughly 25 years after orphans, and the children of the poor, the homeless and the jobless, were targeted for enslavement by the Vagabond Act of 1572.

In 1618 Parliament decreed the abduction of children legal, provided officials received a share of the sale price.

Kidnapping, a term combining kid with the obsolete word for thieving “nabbing” which became “napping,” came into use in the mid 1600s as a term used to indicate an illegally abducted person. This term became known to the literate classes approximately 25 years after the legal abduction of children was codified.

Kid did not enter common usage until 1840s, roughly 25 years after the buying and selling of white children was made illegal in the United States with the final ratification of a 1787 frontier statute.

It is reasonable to assign a measure of time equal to the passage of a generation for the use of a lower class slang term to come to the written attention of the literate upper class of an extremely stratified society. I therefore posit that the reduction of children to an increasingly marketable and sought-after source of chattel labor, to serve as human livestock, was reflected in their being increasingly referred to by the name assigned the young of the proximate livestock they most resembled in form and behavior, the goat.