For browser games it is even more confusing. A browser also downloads a web game to it's cache. But this does not get counted as a download in the dashboard metrics. But doing this with the Itch App does show up as download. A question about this pops up every few months. Like this:
https://itch.io/t/3972731/game-without-downloadable-files-gets-downloaded
Also the download counter only counts started downloads, not completed ones. Like described here
https://itch.io/t/4141152/why-are-some-users-downloading-my-game-multiple-times
That can sometimes even result in hundreds of started downloads, if someone has a very faulty connection.
https://itch.io/t/4061710/someone-buy-my-game-today-and-download-it-339-times
So counting your own downloads as downloads is not surprising. It is probably just a context free number they pull from somewhere.