In one website's subjective ranking. However, their safety record speaks for itself - no fatalities or serious accidents. None of the airlines in the top ten listing in that article come close.
It may be somewhat subjective, and it is probably hard to compare the many airlines that have had no fatalities or serious accidents (reported at least) in the last 30-40 years; like Ryanair has.
But you said Ryanair were the safest of any airline (by far), which seems strange as there are many airlines with similar safety records as Ryanair. Why should they rank above everyone else?
In the end the customers will decide, but hopefully we can avoid another load of customers hitting the ground in MAX (or 8) crash.
I'm not sure about serious accidents, but there seems to be many airlines with no fatalities in the past 40 years. But perhaps Qantas just stays #1 since it has had no jet-plane crash (and no crash at all since 1951). Or perhaps it's the "Rain man" quote where Dustin Hoffman says Qantas never crashes; that cemented their position as the safest airline in history.
Ryanair certainly seems very safe, but with all those new MAX planes, who knows how long that will last.