K.L.
If you are just looking for something to keep him contained and entertained, I recommend an exersaucer or walker (as L. as there is no danger of steps). Also the jumperoo - which is similar to the johnny jumper but doesn't require a doorway. These things are all fine as L. as he can hold his head up on his own - which I assume at 5 months is not an issue.
You are not alone! Just remember to keep note of weight requirements - especially on car seats!