Is age the only measure? What about the contribution or potential contributions to society? Is the life of an 18 year old unmotivated ne'er do well worth more than a 50 year old with children or a 6o yr old who has made great contributions to society and wants to enjoy their last 30-40 years?
There's just no way we can assume that age is the great qualifier.
If one of my 75 year old parents (whom I love dearly) dies from COVID-19, that is less of a tragedy than if a random teenager in my city does. My parent would have lost fewer years or “years of quality life” than the teen.
For the same reason, IMO, if there was only 1 kidney available, an 18 year old should get it before a 50 year old who should get it before an 82 year old, if all else is equal.
In that limited way, I do think the lives of the young have more value than those of middle age or the elderly.