Given your schedule, there is little to do but walk around in the town of Narita a bit. Unfortunately, the big temple near the center of town (Shinshoji) closes at 4PM, but here are some suggestions for other things to do:

https://www.nrtk.jp/lang/en/sightsee...naritasan.html

To do any of these activities, however, you should probably book a hotel in the town itself, since the hotels where JAL sends layover passengers are located out in the middle of suburban nowhere. You may simply want to take JAL's offer of a room, have an early dinner in the hotel, and watch sumo live on TV.

Since you're not a nightlife person, your only option for Tokyo would be to go to one of the commercial centers, such as Shibuya or Shinjuku, and people-watch. The museums would be closed by the time you arrived in town.