"perhaps look into the concept of semiotics?"
Linguistic bat-sign detected! *whooshes in*. Yes your right in the sense that computer languages are languages in the proper sense of the term. What they are not however is human languages that follow a chomsky style deep grammar. Nor does it have any of the floating signification characteristics and multiple other features common to human languages. "Love" can mean a million different things to a human, but "function()" has only one meaning to a computer.
The main reason however to teach foreign human languages to children is because we know from childhood development research that a child that learns a second language at a young age is vastly more capable of learning new languages as an adult. If you make it to adulthood with only english theres a greatly enhanced chance you'll never be truly conversational in another language , even after years of living amongst that language. For instance immigrants who arive with only their home language often have a lifetime of struggling with the new language despite constant deep exposure. Not always, but often.
However children who grow up with more than one language are often adept at picking up new languages rapidly.
There seems to be a mechanism behind switching languages that if it isn't learned early never really works well later on in life. Theres no evidence programming languages however function this way. And THAT is why you teach *human* second languages in childhood.