Indeed, it is not a permanent settlement. Suggestions as to its usage generally agree that is was used for several months a year for centuries or millenia, with gatherings of several groups. The monuments of Stonehenge were built by pre-Celtic agriculturalists in Great Britain, not by per-agricultural peoples. Questions remain: why would people aggregate where they did; how would they sustain themselves in a semi-permanent settlement (months at a time) without agricultural products? (Livestock had recently been domesticated by this point, but need to be moved regularly to graze.)
The assumption of its being religious is simple: it isn't shelter, and it has imagery resembling later depictions of religious figures in the region. Religion here is a more general term to encompass the intersection of culture and spirituality. Was it originally non-religious? If so, why aggregate for months to build a structure, before trade was valuable or very necessary?
Isn't the concept of trade not being valuable sort of contradictory? Even without the concept of individual ownership, the precondition would seem to merely be that something is valued. Trade is not (remotely) unique to humans, and I don't think it's possible that human society would ever have been without it.
I mean trade as an institution, not just sporadic interpersonal bartering and sharing; more like merchants, trade routes, and the like. Exchange is not unique to man; trade, as such, is.
Trade becomes more worthwhile when communities begin to specialise. When people are nomadic, they cross many lands, and can simply find what they want on the way (obsidian from the mountains, shells by the sea, berries, roots, and game in forests). When people begin to stay in one place, long distance travel for trade becomes more valuable. As soon as agriculture develops, we discover that obsidian shards from deposits in the Caucasus are found thousands of miles away in central Europe. You begin to have towns focusing on a specific resource, or serving a trade route as goods and people criss-cross the land (Jericho, among the earliest known cities, for example, was possibly involved in the trade of salt; few things can grow in the soil near it).
You cannot see the difference between two acquaintances exchanging goods and a merchant loading his pack, traveling long distances to make profit from trade?
It is the same as between a spat and a war; gathering in a forest and farming. It is in scale and in character, a different beast.
The assumption of its being religious is simple: it isn't shelter, and it has imagery resembling later depictions of religious figures in the region. Religion here is a more general term to encompass the intersection of culture and spirituality. Was it originally non-religious? If so, why aggregate for months to build a structure, before trade was valuable or very necessary?