Can someone please explain to me what an 'adoptable' is?

Like: [link] and [link]

So... from what I understand you're paying for... the right to use the artist's design? So you 'own' that character? Like, $30 for the chance replicate someone's work? It's like a commission you never asked for.

ANOTHER thing is in the 'Rules' it often says 'Feel free to change the design once you've purchased them'. Um. Whut. So... basically... you're... drawing your own character from scratch. What the heck are you paying this person for then?

AND THIS: 'Character is completely yours after purchase BUT this art and character design is completely mine and so credits would be really appreciated if you plan on uploading it anywhere.'

WHUT. So... you still don't technically OWN the design, even after paying for it??? No, srsly, what am I missing hereee???

Please explain and also share your opinion on adoptables! Would you purchase an adoptable? Is it any different to purchasing an art print? Wtf is an adoptable anyways?

I'm not hating on the people who sell adoptables, I'm just a little confused!