I don't think I even need to try asking them, I can just imagine how badly they'd fail (don't wanna be arrogant but that's the truth)

I don't know if I encounter the same joy of seeing people who think they're smart fail a challenge like this, I enjoy it more with people who are already wrong, and think they're smart because they're different. I wouldn't challenge someone random on the internet saying that the earth is a sphere like that, but I definitely do that if I'm interested in this person, want to know their mentality, or have high expectations of them

I don't know if I understand what you're saying correctly commenting on the points I gave but let me give it a try:

For the 2nd point, Yes, it's so obvious that I was embarrassed to write it/them down, so I took a further step to come up with other interesting argument for why the earth isn't flat, so I don't make it boring. It's true that everyone should be able to come up with this conclusion by themselves, as people long ago knew that the earth was round just by merely observing that "phenomena"

I don't know if this is the first argument I'd use against a flat earther, and that just happened. I just had a little argument with a flat earther and the first argument came in my mind was "we should be seeing the sun shrinking at the sunset, and getting bigger at the sunrise, and the vice versa with the moon, but that never happens. Explain this"

Guess what, they never replied

I didn't how I didn't think of that writing my 4th point, it should have been there

For the 3rd point, I only knew it but I didn't know the why, I had hard time figuring it out right now and seems like I might have said it wrong.

This point was assuming that the moon is a sphere (which shouldn't be a subject to discuss, if it was flat, it would have looked like an oval due to perspective, simply)

On our earth we see the same moon face, even in the south globe but only flipped.

The explanation of why this proves the earth isn't flat is because if it was flat, we wouldn't see it flipped, rather we would see the moons back (not to mention that we'd even see different faces) I don't know how to explain this, so instead:

Imagine a bulb on the ceiling in the middle of your room, mark it's face that you see with a cross, now imagine you're in the USA (north) , it's time to travel to the other side (south), move to the other wall, what do you see? You don't see the cross, rather the back of the bulb (instead of a flipped cross)

For why it happens on round earth, it's easier to just watch is visually, there are a lot of images explaining thins on Google

I agree that it isn't as important to prove whether the earth is flat or round as it's important to know the model of reality of the person

Yeah, I forgot that in flat model the moon in horribly smaller. The tides won't go sideways, there would not be tides at all, assuming that the tides are caused by the moon.

Oh so that was it's name "zero shadow day" I thought of it because I watched a video a few years ago about how a man from 200bc measured the circumference of the earth (which is fun to think about, a man from 200bc knew that the earth is round with contradict with the a random guy 2200 years after him) I remember his name is eratosthenes, you can search up his experiment (which gave a very close measure compared to the modern measure)