How do I even know that other people are even conscious?

More and more I feel like people are NPC's. They are basically robots. I used to think that maybe 50% of people are NPCs but now I think closer to 95%.

If I kick a dog it will jump back in pain but you could potentially build a robot to do exactly that. How would I differentiate a 'conscious' being from a robot or would a robot that would react in pain would obtain consciousness by virtue of being able to do so?

ps. yes im a brainlet please provide guidance. there's no need to insult me.