There is a debate in the Rock art world around whether or not British abstract art predates passage grave art.
Therefore if this was the case, abstract art could be your link to the cave art of the paleaolithic.
Of course different cultures develop different forms of expression of their beliefs.
Our ancestors seemed to have gone down the road of abstract symbols, but then I am applying a modern view point to something I haven't a hope of fully understanding. I see British prehistoric rock art as a lost language which I don't think we will ever truely recover.
As for sculptured artifacts, they are extremely rare ( I won't say none existant because I don't know that as a fact) but my personal theory is that everything that these people wanted to express about their beliefs was done through altering the landscape using earth, stone and wood with the circle as the key to everything.
Today I was fortunate enough to visit a reconstructed henge monument (Maelmin in Northumbria), we were shown around the henge by the archaeologist, Clive Waddington, who had built it based upon a nearby excavated henge. One thing that struck me was the carving of the timber posts to resemble totems, there was no evidence that this had been done on the original but it definitely 'felt right'.
Well, abstract and figurative art (what you call passage grave art) is precisely contemporary according to the pioneering studies being done here. As with the wrong belief that big passage graves predated big ones, it used to be thought that one predated the other.
Funnily enough, cave art was quite a realistic thing (remember the archaeologists thought it couldn't have possibly been done by troglodytes and how many 'believers' died in penury for that) whereas much of the Neolithic has 'abstract' signs (zig zags, lozenges and other symbols). Many of the passage graves have mostly abstract stuff (though what we call abstract can be a picture we cannot discern) though it also includes snakes, people and later weapons, including slightly sculptured stones. That they did not transform 'everything' was deliberate, as they were clearly capable of that and more. I believe they chose certain abstract motifs for some sites/stones as they chose different KINDS of stone on purpose, even in the same grave, say, making up the orthostats that close the main chamber.
The idols are quite common by the way, and I've seen loads. I am actually transfixed by some of the designs on some slate plates and I'd like to print them (I'll send some, eh... annexed to you). In all, nothing resembles the 'naturalism' of the troglodytes during the Paleolithic. But I believe there is a certain 'code' since many motifs are common (like the solar eyes). Cupmarks are extremely common everywhere and concentric circles are quite a thing in other areas. I'll let you know when I have further checked those websites for further clues afield (Brittany and Northumbria) so as to get a global picture.