If you're stood in the changing room holding a pair of jersey shorts, my honest advice is to check they don't go see through when you bend over under the strip lighting, because half the ones on the rail do and nobody warns you until you're crouching to pick something up outside. Other than that, buy them. They're the only shorts I own that I've never once had to talk myself into wearing.
Fit wise, you want them sitting on the hip rather than gripping the waist, because jersey has no structure to hold itself up if it's too big, it just slides and bunches at the back like a nappy. Try the squat test before you leave the changing room, proper squat, not a polite little bend, because that's where the seams either hold or where you discover the inner thigh seam sits right where you don't want it rubbing after an hour. Thinner jersey will show every lump and every pair of pants underneath, so go for one with a bit of weight to it if you're wearing them anywhere you'll be standing about rather than lying on a sofa. Seasonally these are a May to September thing for most people, worn with bare legs, though mine come out year round under an oversized hoodie for the school run or the bin or anything that doesn't require being seen properly. If you've got none, start with a plain pair in navy or black before you touch a print, because the plain ones get worn on repeat and the printed ones get worn twice and then live in the bottom drawer feeling smug about themselves. Once you've got the basic pair down, they pair with almost anything you already own that isn't trying too hard, a plain t shirt and trainers for the day, a vest and the same trainers for an evening where the dress code is "turns up at all". I've worn mine with a blazer once, for a wedding reception that had moved outdoors and got surprisingly casual, and nobody blinked, which either says something good about the shorts or something concerning about the wedding.
Reach for jersey shorts on any day that's too hot for jeans but still needs you looking like you tried slightly, the ones where leggings feel too much and a skirt feels like effort, basically most of July.