That number is not normal, although it could be possible.
The Itch system does not count completed downloads, but only those that have started. If I start downloading your game, the system counts one download, if after 10 MB I have an error in the download, I have to start the download again and if I have another error, Itch will count 2 downloads, even though in reality I never managed to download the game.
So having one purchase or one visit could lead to several downloads. However, 300 downloads, with a single purchase in a paid game, does not sound normal to me.
If it were piracy, the normal thing would be to upload the game to a place where it can be downloaded without having an account, so it does not seem logical to me that it is the case either, since they are games without DRM.
Maybe it would be better if you reported it to support.