The Earth is a sphere, change my mind. pt 1

Here I bring a question I want Flat Earthers to answer in great detail in order to convince me that the earth is flat:

Flat Earther's believe that the earth isn't a sphere and a flat surface,therefore two things must apply:

Premise 1: There is absoutely no curvature on earth therefore everything is perfectly horizontal.
Premise 2: There must be an edge/an end if you will assuming there isn't a flat earther here who believes that our earth is infinite.

Reminder: while answering my question, the self proclaimed "Real flat earthers" do not think a flat earth would be a disc even though you are essentially unwrapping a globe but I guess you could make earth a square or triangle or whatever cause flat earthers do not have a consistent or essential model they all believe different things, apperently to real flat earthers like Eric Dubay and David Weiss it would be a "Level" surface. "Level" does not mean flat when we say level in the context we are talking about the earth it means perpendicular to the vector representing acceleration due to gravity, which points to the center of the earth. Gravity is pulling everything to the center of the earth,so level means perpendicular to that force, in simpler terms: Any tangent line with respect to any point on the earth's surface=level. Oceans are level even though they exibit curvature, and this is how all the water molocules sit as close to the center as geometrically possible.

Now that I have that out of the way, here is my question.

Question: Why can't we see forgein civilizations miles and miles away or hell even the edge on a flat earth? Assuming earth a perfectly flat surface we should be able to see everything in a horizontal line of vision, for all those that believe in the ice wall I guess we should be able to see it for those that don't we should at least see where it ends assuming we have nothing blocking our line of sight, but we do not in fact when we look at the vast ocean from the beach everything seems to curve out of view after 3 miles. For an observer standing on the ground with h = 2 metres (6 ft 7 in), the horizon is at a distance of 5 kilometres (3.1 mi) If you stand in the middle of this mile and measure either way, the earth curves 2 inches either way. If you stand at one end of this mile and measure at the other end it will curve away 8 inches. Why? Because the earth (a sphere) curves away with the square of the distance from where you stand.; 2 (inches) * 2² (twice the distance squared) = 8 inches. If you want to calculate this yourself the formula is: d = 3.57 * square root of h. d = distance in km, h = height in meters in the observation point (in this case the drop). In this case the formula accordingly is: h = (d/3.57)^2. https://www.metabunk.org/curve/ For those of those who believe "We see to far" Provide the calculations to justify why.

Have fun 🙂