And BuiltWith that shows it at 88.5% of the top 1,000,000 sites they look at.
Even without considering what jQuery does, the amount of people that already know it, and the heaps of resources out there around it, yes, jQuery is still relevant. People haven't stopped teaching it either. Literally in schools, but also courses like David DeSandro's Fizzy School. Not to mention we have our own.