Yes, different types. Including glacial erosion, core samples and other sediments. Some are interesting, most are unremarkable to the layman. To academics, they are interesting for the story they tell (shat out of parrotfish for example)

That said, there are many types of beach sand, and within a single stretch of beach, different types as well, segregated by depth for example. They are very interesting for the story behind them. Sort of like how "everyone is unique".

The pictures that everyone is amazed at are relatively low magnification. If those grains were indeed so varied in their shape and colour, they would be easily visible to the naked eye.

Could very well have been other animals over time.

How much of all the planet's sand is on beaches frequenteeed by humans? Perhaps the interesting samples are over-represented but they're still neat.

How does that compare to the quantity of sand already in existence?

Seeing as there's now a shortage of water-eroded sand, probably a good portion of it

What a stupid thing to bicker about. Good work, people on the internet. o_O