The reason the Earth does not seem like it has a curve to the human eye is because when you go outside to observe it, you cannot see even close to what you would need to be able to see to be able to process that there is a curve. Let’s take a look at roughly how far the human eye can see.
The human eye can see 3 miles on average, roughly.. This is not including elevation. Even with elevation, you will not be seeing a fraction of 24,901 miles. That is how large the earth is all around, a bit less on the poles due to the elongation.
Earth not being a perfect sphere (the wobble).
So for one, that is not a correct way to look at it and that point is debunked. So by your logic, to see a real curve or observe that there ‘wasn’t’ one.
I would estimate you would need to be able to see 5-10 thousand miles around if not slightly more if you geometrically cubed or graphed a circle as large as Earth, which is simply, not possible for the Human eye. That would be the equivalent of me basically being able to see from where I am (Las Vegas), to Europe and even then, that is still only 6,000 miles, roughly under 25% of Earth’s max distance all around.
Second point, you mentioned water. Ok, water when freefalling takes the form of a round sphere. This is because water adopts the shape of its container. When it hits the ground it is not flat because the earth or surface is flat, it is /flat/ because of the force of gravity pushing a very easily malleable substance against another harder less malleable substance (Street/ground and friction).
Note how water will /always/ try to move downward, for example.. if water is on a hill it will roll, and how does water roll? It becomes round and a sphere, which then it makes its way downward off of the hill. Similarly, if you put water on a basketball, it will find its way /rolling/ in Sphere shape, down.
Freefalling water is always round, because the Earth is round as well as the forces of which create gravity, also round. (Other, larger and more dense masses)
Other point, debunked.
I appreciate your ability to think about these things, regardless, but there are some misconceptions/misunderstandings about the reality in regards to a few things, and or exaggerations about human sense capability.
also note that mathematically, the Fibonacci sequence, manifests things as spirals of which overlapping spirals, become round.