I've used Ubuntu in the past so that's what I'm thinking of using, but if anyone has another suggestion I'm open to ideas. I'm looking for something user-friendly and lightweight when it comes to hardware requirements. The laptop will mostly be used for web browsing and streaming video, if I can get that to work.
I have a Thinkpad X201 (from 2010) that runs Ubuntu 22.04 with Gnome just fine, all things considered. I think LXQt and Xfce are good, too, but I don't think you need to shy away from Gnome or KDE out of fear of heavy hardware requirements.
Those are all different GUIs that go on top of Ubuntu?
In essence, yes. Ubuntu makes it pretty easy, actually, because each one has a dedicated installer and community.
Ubuntu (default choice) - Gnome Lubuntu - Lxqt Xubuntu - Xfce Kubuntu - KDE.
I'm sure you can check out their respective websites and just pick one based on which aesthetic appeals to you
https://ubuntu.com/desktop
https://lubuntu.me/
https://kubuntu.org/
https://xubuntu.org/
The underlying everything else will be the same. It's all "Ubuntu" at the end of the day.