Is sampling an art, a legitimate part of music or just a nice word for stealing?

it's an art, but also stealing

So basically he make a beautiful piano song much more simple and added some drums on it?

Not true. It was a very obscure forum that is dedicated to nerds looking for samples.
the-breaks.com/forums/viewtopic.php?f=5&t=54558
It had been one of their holy grails ever since the foundation of the site

He turned piano into bass, my dude.

At this point I don’t know if you’re just some autistic sperglord larping or an actual black man who’s retarded

t.racist

So he took a beautiful piano sequence, decreased the pitch to use it as a bass, made it much more simply by cutting like an idiot, and then put some drums over it?

Oh so you are an American or third worlder pretending

*much more simple
you simpleton

pretty sure the producer called it out originally but either way 15 years is impressive for how blatant of a sample it is