I know I'm going to come across as a heretic here but I'd recommend a Remington** 1100 Light 20. I believe Remington also offers a "youth" stock for this that can easily be replaced with a longer stock later.
Another reason for this recommendation is an 1100 is a noticeably light kicker which to me is a big advantage when starting a youngster shotgun shooting.
Jim

**If these are no longer made you will have to look for a used example.

The 2nd Amendment IS an unalienable right.