Hey!
The reason for multiple pages is webgl builds: you can only have one webgl build per page.
So, i keep the stable version in the "main page", and create other pages for secondary and archive versions.
Concretely; this was the jam page, but as I updated the game I still used this page (so players got notified).
Then, the jam version was lost, so I created a dedicated page for to archive the jam version.
Then, I wanted people to beta-test the game, so i created an unlisted page for it.
Web is very important on itch:
* webgl builds increase the play-ratio: It is hard to get people to play your game (30-50% of the people dont even press play on the webgl build). Additionally, downloadable versions are more work (as you need multiplatform builds), and can be scary for players, as apps are not signed by default (and you get a warning)
* webgl ensure that people play the latest version of your game: If you want feedback on an ongoing project, this is very useful.
I am not sure it is the best solution, but it is the one I found.
I hope this helps.