Capitalism really is trading goods for currency, and allowing lending and investment.

That’s commerce. Commerce predates capitalism, by a lot.

Capitalism also involves other things that go beyond basic commerce, such as systems of property law to incorporate quasi-sovereignty to capital ownership. That’s more or less where we get the default model of businesses as de facto dictatorships ruled by the owner, vs. being democracies organized by stakeholders or participants. It’s a big, deep subject that’s unfortunately talked about in reductionist terms a lot. It’s probably not helpful that a lot of early (and recent) scholarship on capitalism seems to frame itself as revelation of the nature of capital and markets, as if capital and markets are natural forces and not man-made things.

This last bit- treating capital and economics as if they were laws of nature (instead of being contrived by men)- does a lot of work to obfuscate fundamental systems of power, which in turn helps keep that power unaccountable. One major source of tension between capitalism and socialism has to do with whether the sovereignty of ownership ought to be democratized or subject to democratic accountabilities.