I don't think the Marxist definition of capitalism lines up with the colloquial definition. Colloquially, it's thought of as systems in which money is exchanged for goods and services. As opposed to communism, where it is not. (These are both oversimplified)
When people say capitalism has been around for thousands of years, what they mean is the colloquial definition. Redefining their terms with the Marxist version doesn't address their actual point.
When you survey people on the street, would they use that definition? English isn't a prescriptive language, the definition is what people use it as.