Funny... my family always had the heirloom ornaments, and they always went up on the tree, kids or no kids.
And we always participated in tree decoration... as soon as we were old enough to stand steady and place an ornament.
The ornaments all had stories - even the paper ornaments from the Depression.
Certain ornaments were left to Mom & Dad to place... that was part of the tradition.
Tree decorating was a party.
We were admonished to be careful.
And we were, 'cause we were afraid that we'd not be allowed to participate if we broke ornaments (altho that happens no matter what, and we were always forgiven in a good natured teasing way, none the less, you feel pretty bad when you know the story of an ornament you just broke...).
We were shown how to clean up carefully... maybe it took a couple of years before that was part of the consequences of breaking an ornament, but I do recall Mom sternly instructing me on
safely cleaning up the broken glass, and she was a whole lot taller than I was.
That was just one of those skills that a kid was expected to learn in those days...