Gravity is fake - it's just density and buoyancy

"There is no gravity. Things fall because they are denser than air, and light things float up - it's just density and buoyancy."

Density explains buoyancy in a fluid - why things float in water or air. It does not explain falling in a vacuum, where there is no air to provide buoyancy at all. The classic test was done on the Moon, which has no atmosphere: in 1971 astronaut David Scott dropped a hammer and a feather at the same time. They hit the ground at exactly the same instant, confirming Galileo: in a vacuum all objects fall at the same rate, whatever their mass or density.

Apollo 15, 2 August 1971, broadcast live on TV: hammer and feather land simultaneously on the airless Moon. If 'density vs air' were the mechanism, the feather would have drifted. On Earth the same experiment needs a vacuum chamber - and gives the same result.