Unless you would love to lay out at the pool or beach 12 hours a day, there isn't a heck of lot more to do there. If you don't have a car your really going to climb the walls and if you do it's a long drive to anywhere.
I was just there in early May with DS, DIL and 3 grandkids, I'm not a pool or beach person so I was bored silly except for the day we played golf. I would never consider going there solo, but that's just me. I make several trips a year to WDW solo and never run out of things to do or places to go or dine and I have a much better pool to lounge at if that's what I chose to do (not).
Whatever you decide I hope you have a great solo trip.
I'll be there Memorial Day weekend solo as I do every year.