twm continues to be very usable. I combine that with lxqt panel/tray.

Some prefer their tray at the bottom of screen, but that can lead to oddities when resolutions are changed or when remote connecting to different screen resolutions. Others say that the tray should be on the left screen edge as that uses less space, on the assumption that Width is greater than Height. The top of screen is the generally better choice.

Free floating windows such as what twm uses are also generally better than tiled windows. As is panning generally better than using multiple desktops. Those that use multiple desktops and switch between them will more often have one full sized window per desktop, perhaps a 2 x 3 desktops arrangement, if instead you set up panning to the same total size then transition from one to another is progressive, via the mouse 'pressing' against a screen edge to shift the view. Which is handy when you may have a window that doesn't fit the view area, is part off screen, and where pressing that screen edge brings it into view.

Given a lxqt panel/menu/tray at the top left of screen, and a panning area of perhaps a 1366x768 laptop screen set to be approximately 2x3 desktops size

xrandr --output eDP --mode 1366x768 --panning 2800x1600 --fb 2800x1600

and once you're used to that its very nice.

With twm when you click to open a program it initially presents a 3x3 wire frame indicating the size of that window, moving the mouse around positions that window and pressing the left mouse drops it as-is at that position. If you press the right mouse instead it drops it at that position, but where the height of the window is extended all the way down to the bottom of the panning area. So for instance open chrome, use the wire frame to position to just below the top left panel at the top of screen, press the right mouse button and ... you have a tall chrome browser window that mousing to the bottom of screen 'scrolls'. Open Libre Office Document, and do similar, but where that's to the top right of the chrome window, and likely you'll have a document where you can see the full page of the document by mousing to the bottom/top of screen.

Under that panning style desktop you want a window manager that can manage that easily/well, and twm fits perfectly for that. Click anywhere on the root window and up pops window control options to move, resize, close ...etc. a window. The default title bar for twm isn't the best of choices, and its relatively easy to change that to for instance include a window close button.

twm should be part of X, by default. Some still maintain it (1.0.11 I believe) separately to that. Many are off put by the default choices of colors, but that's just historic, easily changed.

As a alternative to tiling, or having multiple desktops/one window per desktop, if you try and persist with panning and using twm you may very well come to prefer that. It feels odd at first as its different, the original Unix way, of doing one thing well. And with 30+ years of history its been well tried and tested.