Ok, so the reason why you see up to a certain point on the horizon is that the earth is round. Because the earth is so big, the curve is too small to perceive with the human eye in most cases.

Your argument is that we only perceive something at a certain distance, like a game rendering scenery? That's obsurd. If that's the case then why the hell can we see stars millions of light years away and not 100km in front of us?