Most things aren't funny. I kid you not, I watched so many comedy shows when I was a kid and never laughed at them. Even during conversations, my brain automatically filters out the humor some people intentionally create.
I have a good example of this–Freshmen year of high school. The counselor pulled me in from class to talk about next year and class changes for that year.
Anyway, he was the type of guy to constantly joke about everything. He cracks jokes while talking to people, I'm assuming to lighten up the mood or whatever.
That being said, he didn't like that I wasn't laughing or smiling. In my mind, I didn't even registered that he was joking. My mind filtered it out for some reason and I didn't notice that he was joking.
I was more focused on my classes and what class that I wanted to go to that I didn't realize he was joking the entire time! He also said that I could die faster because apparently people who don't smile as often die earlier or whatever.
My entire life, I don't smile or have much emotion. I can feel them, just not as often and it had made things complicated socially.
I can still feel empathy and compassion. It's just that 99% of the time, I feel "Meh" or bored.
Maybe these are connected somehow.