The first two are pretty dreadful (although the luggage is amusing) — and they do introduce the core concepts (who Rincewind and the wizards are, the Librarian, what the Discworld is like) ... so, they're not entirely irrelevant.
But if you're concerned about there being too many then read the Watch and Witches ones (plus at least Mort)
Equal Rites (introduces the witches)
Mort (introduces Death)
Wyrd Sisters
Guards! Guards! (introduces the Watch and Havelock Vetinari)
Witches Abroad
Lords And Ladies
Men At Arms
Jingo
Carpe Jugulum
The Fifth Elephant
Night Watch
Thud!
Snuff (introduces the goblins ... whose fate will make you cry)
You'll miss out on the Librarian (who is cause for much merriment) and the significance of the wizards (and they are the counterpoint to the witches), but if you're worried about not being able to read them all then the Watch and witches are the most important ones to read.
You'd probably also appreciate Small Gods, Feet of Clay and (quite possibly) Hogfather and Thief of Time.
Going Postal is also particularly good (introduces Moist Von Lipwig).
Also, if you have the time/inclination ... The Wee Free Men (introducesTiffany Aching and the Nac Mac Feegle, who are really fun) — whatever you do, do not read The Shepherd's Crown until you're absolutely certain you're done reading all the others though (you can read his stuff out of sequence without losing too much by messing with the continuity but it's the end of the entire Discworld and shouldn't be read until the end).
https://www.discworldemporium.com/content/6-discworld-reading-order
Not reading the wizards stories might result tin an out of cheese error, however, and then you might well be the cause of the end of Life, the Universe and Everything (Ook! 😮) — just a friendly heads up.
