The Windows mechanisms you're mentioning were also added over the course of many, many years. Much of Windows also happened a long time after UNIX signals were invented.

If you're including all that other stuff, it's probably fair to include all of the subsequent development of notification mechanisms on the UNIX side of the fence as well; e.g., poll(2), various SVR4 IPC primitives, event ports in illumos, kqueue in FreeBSD, epoll and eventually io_uring in Linux.