Sounds like you need to set up the Jellyfin server as a windows service so it starts without logging in. I’m surprised it doesn’t do this automatically as part of the installer setup.
Alternatively you can just set up auto-login for your windows user account, but that gives you no security from local access.
There isn’t a true replacement for Wordpress because of the sheer availability of plugins it has.
But for simple sites like blogs and personal sites Grav CMS is one I’ve used, and it gives you a web admin panel similar to Wordpress, so the learning curve isn’t too bad.
Drupal also gets mentioned a lot as a replacement.
There are also static site generators like Hugo, but those require learning a lot about the specific one you use, and are pretty complex to use, and if you need non-static content like a web form or something it can add a lot of complexity to your whole setup.
Yeah the first run experience really needs to be tweaked so it’s a normal window.
Bluesky is a lot easier to use vs fediverse stuff, discovering stuff is also easier in my experience vs mastodon.