Well, I’m not counting jewelry because surely everyone has decades-old jewelry, right?!
Oldest item that was new (vs. vintage) when I got it is probably the lacy knit brown cardigan I was wearing in one of the tube skirt try-ons. It goes in and out of favor but I think it was a gift from mom some time in the 90s.
Most worn, the dark brown leather jacket I have on right now, bought 20-25 years ago. (Also a bit unfair because of course outerwear pieces get worn more often.)
Next? No idea, but I keep most of my clothes for a long time.