Honestly, it sounds as if you set reasonable limits so I would just ignore your senior citizen neighbor. The reality is that we live in a crowded area and reasonable noise level, such as the basketball playing as you described, is normal.
Your hours are more than reasonable. We don't let our kids play loudly outside until after 9AM on weekends, nor do we mow grass, use the leaf blower or any other loud yardwork before 9AM. That's being considerate of your neighbors. After 9AM, well, people need to be able to get that stuff done. We also don't let the play loudly outside after 8:00. If the neighbors have a kid with an earlier bedtime, they let us know and we respect that. We do have neighbors (like the PP) that let their dogs out at 6AM, leave them there for a couple hours during which time they bark and get into fights with each other. We've never spoken to them about it - although if I had a newborn, I just might.......
It's very nice of you to make the basketball goal available to other kids. Ignore the crotchety neighbors.