The government already restricts speech. Libel is an obvious example. We therefore need to debate what the concept of free speech actually means and what the practical implications of the 1st Amendment are because they clearly don't mean that speech is completely unrestricted.

OP is suggesting that anyone who comes to that debate with definitions that are more restrictive than OPs should end up in prison. How is that not inherently a restriction on the speech that one can make about free speech?