The extremely unlikely, a d actually entirely coincidental, fact that our moon happens to be precisely the right size and distance from the sun and moon to perfectly obscure it.

If it were further away or smaller, it wouldn't block it out completely and we'd just get annular eclipses, which doesn't let you see the corona, just a ring you shouldn't look at directly without eye protection.

If it were bigger or closer, it would obscure the corona and we'd just see darkness.

Stellar bodies lining up is perfectly normal and commonplace. Them being exactly the right size shape and distance to create a total eclipse is fantastically unlikely.
Doubly so when you consider that the moon is slowly moving away, and so a long time ago the moon was too big in the sky, and in about 50 million years it'll be too small.

Something so unlikely happening during the time there's intelligent life on the planet that can understand and appreciate it is, literally and figuratively, astronomicaly unlikely. 😀

The formation of our moon isn't terribly likely to happen frequently. Also the moon, star, and planet have to be in the correct places. Our moon won't create perfect eclipses in a few hundred million years

https://fivethirtyeight.com/features/earth-has-the-solar-systems-best-eclipses/

No planet in our solar system has a moon large enough to completely eclipse the sun from the planet surface POV