I think a problem with this analogy is you are comparing children not dying from a disease they do have to an airplane which doesn't have the problem you mention.

Lets square up the analogy. So there are 0 deaths for children that get coronavirus, and about 1/5 of the cases have been among children.

Planes crash, and out of all the planes that have crashed about 1/5 of the passengers were children, if 0 of the children died would you interpret this to mean children can't die in plane crashes?

And yes, basically I would interpret it that way if it were true.

Ok, maybe I can make it closer to your analogy:

There were 0 deaths for children that get caronavirus, maybe you think children are much less likely than adults to die if infected? Planes crash, if the A380 has never crashed despite millions and millions of miles in service, would you interpret that to mean that an A380 is much less likely to crash than other plane models that have flown a similar number of miles and had a bunch of crashes?

Again, yes, that is just how statistics work.