HTML has had checkboxes since at least version 2 (1995), so just use those if you want to do multi-select using checkboxes. I don't think you can do shift-clicking to select ranges though (without resorting to js) but control-click is of course redundant as that is just the default behavior for a list of checkboxes.

This is pretty much correct, though I feel there's some finer points depending on the number of options (5? 10? 50?) and the expected number of values chosen (2? 4? 10?).

Checkboxes are a good choice for a small number of options: https://m3.material.io/components/chips/overview . I'd say past a dozen options though this starts to become unwieldy.

Tag-style multiselects are fairly common (see https://react-select.com/home for an example). These are good where the number of values a user is expected to have selected is small (less than five imo) but the number of options is large enough to make checkboxes impractical. If you're expecting a higher number of things to be selected, you could have the option list stay open after an option is clicked, so they user doesn't have to reopen it each time they want to add an option (and, in fact, the "Animation" example does precisely that).

Two column designs ( https://crlcu.github.io/multiselect/examples/search.html ) have mostly fallen out of favor, though I feel they still have their uses for larger lists with large numbers of selected values.

> Most normal users (aka if you read Hacker News, you're not one of those) don't and won't know about shift and control clicking.

My boomer parents do. Most users I've seen in the wild do.