Hello All Mummies!

I noticed that my 15mos. old son is not that interested to all the toys I bought for him.... like toy cars, robots, balls (for basketball) and etc. He only played it once or twice but after that, he don't want to play it anymore. But he loves to play anything that is inside our house like things in the kitchen, our chairs, things in the laundry area and those dvd's that he usually watch like baby-einstein, nursery rhymes and etc... Can I ask for any suggestions or advise why my son has no interest in some toys? Is there something wrong or is it normal? Thank you so much in advance