Mystery Solved!

They're Ken's shoes! (doesn't he have weird socks??)

This is my Ken doll from when I was a kid. I didn't keep it, but my Mum did. She kept a lot of toys, and has decided to give them to me to sort out. They're all going to charity, bit by bit. Ken somehow managed to poke his feet out of the black bag he was in and lose his shoes!