We haven't yet seen Harry's reaction to the fact that Flitwick invented a Charm; presumably he will update his model of the nature of magic when he has time to process this.

Without knowing the details of the process of researching new Charms, we can't really differentiate between "invented", "discovered", "created", and "learned". Flitwick is not a scientist and I don't trust him to report the difference correctly. The discovery itself is not on-screen.