Windows 2.0 for i386 was the first to introduce protected mode and preemptive multitasking. These features had to wait for Intel but it was available in 1987.
I don't believe Windows 2.0 implemented preemptive tasking, can you show a reference so I can learn?
1 - https://en.m.wikipedia.org/wiki/Windows_2.0#Release_versions
2 - https://liam-on-linux.livejournal.com/78006.html
3 - https://lobste.rs/s/4xfswa/what_was_difference_between_windo...
4 - https://anotherboringtopic.substack.com/p/the-rise-of-micros...
The Lobsters discussion was very interesting. Some people in there were extremely knowledgeable, but also very confrontational. Coming straight in going "that's all wrong!" is not a productive way to start a discussion IMHO.
I didn't get any very firm conclusions from it. There are some very knowledgeable people out there on the WWW claiming, with convincing arguments, that Windows/286 couldn't run in 286 mode and only gave you 640kB ("conventional memory" in DOS terminology)+ 64kB HMA.
Others, including from Microsoft, say no, Windows/286 did run in protect mode and could access 16MB of (segmented) RAM.
I do not know for sure who is right.
(Windows 3.x 386 mode is similar, with Windows 9x stuff in the Windows VM can pre-emptively multitask, mostly).