How come I enjoy being alone, uncomfortable socially and I lack empathy?

I still have compassion for others. I’m able to understand everything. In terms of my personality, most I’m someone that enjoys being alone and when people talk to me I shut off and give short responses; it’s because I don’t understand where they’re coming from so it’s difficult to respond, I can’t just say “I don’t know”.
But interacting with a cashier or a gesture to a car or bike to go before I do, is fine. I get easily confused in conversations and even when I can hear the person speaking to me, I still didn’t understand what they said. People find this frustrating I believe and I think I can pick up they’re irritated.
How come I enjoy being alone, uncomfortable socially and I lack empathy?
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