Toys for 6 month old?

Hey ladies, if you have a 6 month old or older what were some of their favorite toys? I found my son is getting bored so easily with his toys now. He isnt interested in his playmat anymore so ive turned it in to a tent, he honestly spends no time on his back anymore. Immediately rolls on to his tummy and tries to crawl. He likes hitting and slapping and kicking, he has a drum and loves it but i need other ideas to foster those skills in a positive way. Also just any fun toys you noticed your kid liked. I bought him a ball pit to try but cant find balls for it? Anyone know where i can get some? I do toy rotation as well but i just find he isnt interested anymore even when i bring out other toys