Why do objects slide down hills?

I’ve been in r/globeskepticism for a while, and I’ve familiarized myself with a lot of flat earth proof and theories. (If you’ll look at my user flair I’m doubting the globe. Personally I see myself in a spot where either globe or flat could be true, and I need personal evidence to know for sure which is true.) Other questions I’ve had I’ve found an answer to, but there’s on I can’t think of. If gravity doesn’t exist, then what would make something slide down a hill? If it’s just buoyancy, then why wouldn’t something stay at rest on a hill? Since things are just being sorted out by their density. On globe Earth I think it makes more sense with gravity in the equation because everything is pulled towards the Earth’s center of mass, it’s core. I’ve heard that a reason that things are affected by buoyancy is because of electromagnetism. If that were the case, then, once again, why would something slide down a hill instead of just sticking to the side of it? There might be something I’m missing, so explain this to me like I’m five. Thanks for reading!

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