1, if gravity is non existent, than how can the Earth be at the center of the sun and moons orbits, and rotate on a consistent path for many years without any other forces acting on the sun and moon to control its movement and rout for the sun and moon to be bound to a rotating path above the Earth some force has to be acting on it to move it in that confined and consistent motion.

2, if gravity did not exist, stars could not exist, the reasoning for this is because of the unstable nuclear fusion that is literally happening at the core of the star and all the violent energy that is escaping from the core and away from the surface of the star, thus resulting in all stars to have to instantly explode without an extremely strong gravitation field (compared to that of the Earths) compressing all that matter. Also there would actually be nothing to be able to compress matter int he first place and form a star or moon, or even a flat Earth, without gravity loos objects that cannot bind together would crumble and fall apart, such as dirt, sand, and many types of stones and other materials. Nothing would even be able to form.

3, if gravity did exist, gravity draws all matter to the center of mass and keeps compressing the matter to take up the smallest volume possible, so the flat Earth would ultimately crunch over, crumble and collapse on itself towards the center of mass forming a spheroid. If this never happened because of magic or something you cannot prove then gravity would become massively skewed the further out to the edge you wen't eventually forcibly angling you so much that you feel like you are climbing an steep mountain.

4, no one can say that the flat Earth is accelerating upwards which makes it so when we jump it keeps moving upwards and catches us. This is the same concept as relativity which you cannot deny because this is something always experienced when inside of a moving object, such as a car or an airplane, when in a care going 100mph, and it goes to 0 instantly you will remain moving at 100mph and fly forward, you carry the same momentum as the flat Earth when it moves upwards and almost everything will ultimately actually float away from the flat Earth, not only that how is that atmosphere even contained on a flat Earth, you cannot say that a massive dome is on the Earth next... Don't even attempt to bring up air resistance, for an object as large as a human, air resistance will play an extremely small roll and will defiantly not allow you to fall back to the Earth from "slowing down" after jumping as fast as how it currently happens.

5, the definition of down or level is parallel to our location int he gravitation field, aka which direction gravity is pulling down on us. An airplane does not need to adjust its angle when flying because gravity forces this on its own, for an airplane to fly in a straight line and move against gravity it would have to adjust its angle against gravity, which if this was done with a tank of water in the airplane, this would disprove the water always lies flat claim as it will eventually skew to a new angle of gravity or a new "down". For the airplane would be carried and retain the same momentum it gained from the Earth spinning when taking off and from the atmosphere moving with the Earth. It is exactly like moving up to the drivers pit when in a limousine and then walking back, it feels no different unless a sudden change in momentum is made or the limousine turns, a car just driving on the earth simulates the same effect or a drone / helicopter riding above the ground.

6, No curvature from seeing objects that should be hidden, atmospheric refraction is a real thing and is a very powerful illusion, the same thing with seeing the sun and moon during times you should not be seeing it. Saying to use your basic senses and observations is a terrible thing to say and do as those forms of analysis are some of the most deceiving qualities a person has for observation. There are plenty of illusions for the eyes, ears and touch which easily trick you and everyone and you are your brain and your brain is you, so your most basic observations can be easily fooled.

7, on a flat Earth, everyone will "always" and I stress "always" be able to see the sun no matter where they are, this is the same concept as seeing stars in the sky, their light is not powerful enough to shine brightly on the surface of the planet, but are bright enough for us to see them, same with the sun. Yet on this Earth, you will never see the sun during the day unless some sort of rare event of again atmospheric refraction occurs, and on a flat Earth this will 100% happen every night, and since the sun is supposedly so close, it will defiantly be larger and more distinguishable from other stars.

8, when it is cloudy and the suns rays shine through at angles, this is an illusion, light is always scattered in the atmosphere, this is why the sky shines blue as that the blue wavelength gets scattered int he atmosphere more than the red wavelength, and during sunset and sun rise the opposite is true. Light gets scattered for different angles and wavelengths, when clouds obstruct many beams of light, the unobstructed ones will be more dominantly visible over the obstructed ones creating pillars of light that angle outwards, what is failed to understand is that they are being perceived from 2D plane failing to understand it in a 3D plane, the lights viewed from above will scatter in random directions and not towards a light source.

9, weight depends on gravity so this cannot be made as an excuse, and if gravity did not exist, nothing would be grounded and everything would have no weight as it is not defined by matter but by gravity's effect on matter as well as its density and many other properties which gives it its weight.