Nothing is "just a social construct". Even social constructs aren't social constructs.
Let me reverse that point of view to an extent: assume
everything is a social construct. What would that mean? I understand it to be something that would not be here were it not for a collective effort from the society. In that way, isn't language a social construct? After all, our ancestors managed to communicate in some way and their children up to us upheld this tradition, adapting language so that it can be easily understood by our entourage. That's also a thing with body language, thumbs up is considered an offensive gesture in some cultures, and nodding/shaking your head has reversed meaning in Bulgaria. It all could have been different, had people not agreed that this is the wae. Obviously, you could argue that all of our thought is based on language, so everything is ultimately constructed.
But let's have another example. Take science. Here, you have the element of collecting data. But not all data is correct, some can be flawed and misleading, and of course it can be misinterpreted, for instance leading to hasty conclusions and the supposed emergence of a new theory when there isn't enough evidence to suggest that. Let's assume that there is a reality (duh) and that some of our theories manage to grasp part of what's really going on in the world. Yet, theories can be abolished. Take aether, which turned out to not exist in the end. You could imagine a history of science where nobody would ever assume that aether existed. Now imagine that science is flawed in the modern day and that, for instance, the theory of quarks is wrong for some reason. It could be that there is a parallel universe in which quarks were never assumed to exist, then. Sure, if there's a real world which is governed by a set of laws, it limits human creativity in that regard since it obviously must be grounded in observations to some extent. The point is, the theories aren't directly based on what is real, but what we understand to be real and what we think we can assert from the data. They're social constructs.
And so on, you could make cases for other things as well.
You don't seem to be very rigorous in your statement, the first sentence argues that nothing is
just a social construct, but then you proceed to maintain that nothing at all is a social construct, which is rather confusing. You never define "social construct", I think it would help to see what you really understand by that. It could be that you didn't understand the concept, or that you define it differently than I do. It seems to me that if you somehow imply (as you seem to be doing) that a social construct ceases to be a construct when it has real consequences in the state of the world, then indeed no social construct can exist since every action brings about a change in the world. But then again, I don't see where that implication would come from.
To respond directly to your argument, let's take one of your sentences:
Time isn't a social construct because it affects us no matter what we do.
The concept of time is a social construct, though. People agreed on a conception of it and that's why we're able to even have a conversation about it. To come back to my earlier comments on science, it could be that we are mistaken. Perhaps time is an illusion, somehow, as some theorize (I believe), and it doesn't really exist. Perhaps what we call "time" isn't a real entity and is in fact several other phenomena acting together in some weird way we don't understand. Finally, since we might know so little about it, it could be that it does
not always affect us no matter what we do. There's always a barrier between reality and what we understand it to be, and the gap is bridged by construction in order to try to make sense of the world.
