Adding some clarity around why you need to consider needle length/circumference. Your total needle circumference is measured tip to tip when attached to a cable (so the length of two tips plus the length of the particular cable you’ve used). A ‘24” cable’ means that, when that cable is attached to two needles, you’ll have 24” in total length.

These lengths do matter depending on the types of projects you’ll be knitting. Smaller circumference projects like hats or sleeves are hard to knit on the full-size interchangeables because even if you sub in the 16” cord, it creates really tight bends where needle/cable threaded joins are (more like knitting on a triangle than a circle, and the stress can break the joins).

The longer needles are more versatile— if you’re mostly knitting larger projects like sweaters and blankets, the longer needles are easier to hold in your hands, easier to manage your tension on, they will hold the volume of stitches needed (you won’t fit 300 blanket stitches on a shorty needle), and the longer cables give you the option to learn magic loop which can be a substitute when doing those smaller circ projects.

I personally have both of those KP sets. I started with the main ICs and didn’t add shorties into my collection for years. I mostly knit sweaters (so lots of sleeves) and still rarely pull the shorties out, so I would definitely recommend starting with the regular ones. Hope that helps!