BSD was the main open source option for a little while, but got into a big legal battle that dragged out for years, and Linux came out during that time and took over. BSD never made a major comeback because no one really needed it anymore after Linux came along. It's still around because it was already done, so people have just had to maintain and update it since then. Hurd is non-existent for reasons that are contentious, but everyone agrees that at least one of them is that a lot of people got excited about the Linux kernel and lost interest in Hurd and switched to Linux development instead. It is possible that if more people had stuck with it there would have been a real, useful Hurd instead. These aren't even the only alternatives that were being worked on at the time.

The idea that any one person could will an entire operating system into existence by making a hobby kernel that fit a useful niche at the right time is just patently absurd. Linux is great, and Linus Torvalds is a good steward of it, but no, he is not the only reason why open source operating systems are popular.