Can someone explain the GoPro range of cameras?

Okay, so I was looking for a cheap camera I can use underwater and not worry too much about trashing, I saw the 2014 "entry level" gopro Hero, and it looked Ideal for the purpose.

I Saw one on Ebay in an auction and was the winning bidder - not surprisingly.

Turns out, this is a standard definition model, with a full-size SD slot and it uses aaa batteries.

Now...how can there be models so drastically inferior to "entry level". It's misleading. I see quite a few people are taking advantage of this on Ebay with very vague listings selling old SD gopros to people who think they are getting the 2014 model. And they are not breaking any of Ebays rules, so there is nothing you can do. For some reason, GoPro have "reset" the name "Hero", and are re-using it.

So...other than the 35mm original, is this more or less correct:

First there was the Hero. In standard definition. Then there was the hero 2 and possibly hero 3. THEN there was the HD hero and HD hero 2, 3 etc. Then the naming convention was re-set and they re-used the name "hero" by itself for the current HD entry level model and re-used Hero 2, and 3 only without the "HD" designation, and with various colours used as the different models within each model. THEN we got "plus" versions of those numbered models.

So, what's to stop people from listing their old SD "hero" on Ebay as simply a GoPro Hero, (Since that's the name) and letting people think they are getting the current model which uses exactly the same name?