No, in that link I can't rent any data, there I can buy ad space.

The data is part of the rental - you can only use it tot target your ads.

Please, point where in the Ads documentation where it explain that USER data can be seen by advertisers.

It can't. It is processed on the advertisers behalf by Google.

If Google allowed it to actually be downloads, their competitors would be able to use it, so the processing is done within Google.

That doesn't make it any less of a product for advertisers.

So no, data is not rented, thanks for acknowledging that.

I didn't acknowledge that. Renting the data doesn't mean third parties see it - since there would be no way for it to be 'returned'. Instead a program is executed on their behalf.