Why some people think cats aren't playful or have personality.
Simple: People don't play or interplay with cats the way they do dogs. When I adopted my current feline, I was told he didn't play with toys at all. I tried him for more than 15 seconds on that, and he did!The foster who'd cared for him before was a blonde co-ed with other things in life. I have no life, so I had the time. Similarly, his sister before him supposedly NEVER went outside. With some coaxing, she did, and sometimes WANTED to go outside.
So, actually PLAY with your cats. Actually affirmatively have something to do with them. As content as they may be left alone, a lot of that is resignation to their situation. Give them love. They have so much love to give you.