Due to gestures vaguely, everything going on right now with WordPress, I thought I'd put together a list of alternative CMSs that better fit the criteria someone might have for their website. The modern CMS landscape is super broad, with the very definition of "Content Management System" being stretched. Some see it as a full-package website platform, and some see it as just UI for their content stored elsewhere.
The criteria for this list are "Can it be downloaded, dropped onto a server, and you'll have a website?" This eliminates API and git-based CMSs, which I enjoy using; however, wiring a daisy chain of tools is just not viable for many.

People will already know I have a soft spot for Ghost. But what you might not know is what I'd recommend for hosting.

Magic Pages is what I'm using for Design Systems WTF, and it's been great! The uptime is good, the price is very reasonable, and Jannis provides a personal touch with support. In addition, this sidesteps Ghost's own hosting option (Ghost Pro), which I would be wary of due to past experiences with other customers.

I have not used Kirby in client work, just briefly as a local setup, but it seemed like a smooth experience, and I only heard good things online. It's file-based, which seems super appealing to someone like myself who gets cold sweats when opening a database.

Indiekit seems like an interesting option; it's also file-based but needs a database to manage existing content.

It's a bit more of a commercial option with Craft CMS, but it does offer a free option for solo creators. Warning, though, as you'll need to spend time architecting your content structure by the looks of it.

ClassicPress appears to be a direct fork of WordPress but at version 6.2.3. It seems perfect for anyone looking for "the good old days." However, it uses the official WordPress plugin API, so it's not a 100% clean break if that's what you're going for. Thanks to Pelle Wessman for this suggestion.

I've had several people suggest Statamic. It does look pretty good, plus they have a free solo plan (similar to Craft CMS). I think if the cofounder hadn't brazenly endorsed a horrendously damaging politician, I'd have tried it.

Probably the most comparable CMS to WordPress, Wagtail is open-source and created by Torchbox, which is just around the corner from my co-working space. I've tried it extremely briefly, but the installation was pretty smooth, as far as I recall.

The text pattern looks extremely utilitarian, with a text area, a title, and publishing options. If that's all you need, then I guess you're all set 👍🏻
I was going to suggest Perch and Buckets on this list, but public activity seems low for both. The Perch website even has SSL certificate issues, which isn't a good sign. Check them out if you're interested, but you have been warned.
Honourable mention

Many years ago, I contributed to Anchor, a humble PHP-based CMS that grew a little community around itself. Sadly, the creator, Charlotte, passed away in 2020, and the remaining core team couldn't keep the project going while juggling other responsibilities. I think of it fondly and wish we could give it the time it deserves.
The theming and custom types aspects were wonderfully simple; heck, I even made a whole site dedicated to themes and sites built with it:

I'll try to keep this list up to date if I recall any others I've used in the past. Hopefully, you find this useful if you're seeking alternative CMSs.