Keyword Conversations

Here's a thing that happens to me somewhat-often. In a conversation, I'll try to make a specific point on a specific topic, e.g. "I worry that it's fundamentally impossible to communicate with a cat."

And the other person will respond with (what seems to me like) an irrelevant riff off a keyword in my comment: "I saw a really funny cat on the way over here! His face looked kinda like a potato."

There's a few different things that might be going on, on any given occasion:
1) the person finds my comment super boring, and is just doing their best to pivot from it to something more interesting
2) the person couldn't figure out what I was trying to say, and is trying their best to say something at-least-tangentially related
3) the person is replying directly to my point, but I'm failing to grasp the connection
4) the person has a different model of how conversations work

I'm truly interested in any suggestions for what (4) might be. If you recognize yourself in either half of this conversation, I'd be very curious how you understand the dynamic.