I do want to note that there are some adults who will not receive a check: dependents. Mostly younger adults (college kids, for example) and elderly parents who are dependent upon their children.
There are also some ‘donut hole’ children who won’t qualify for the $500 check most likely. I have a son who was 17 last year and turns 18 this year - the 2018 tax act redefined children (for Child Tax Credit purposes, which is what it appears will be used to define children for stimulus payments) as those 16 and younger. As such, he probably will not qualify for a $500 stimulus credit.