After some serious introspection, it finally dawned on me that the "meaning" of wallmaking was really deep...
I concluded -- perhaps not surprisingly -- that it's connected to an innate quest for immortality that is inherent in humans. Our mortality is clear to us from an early age and, although we do not acknowledge it very often, I think it's always there, somewhere in the back of our mind. Far from reneging our mortality, I think it's a good idea to regularly remind ourselves of it. I do. And I find our limited shelf-life inspiring rather than depressing. If we're here on earth for such a glimpse of time (insignificantly brief in cosmic terms), then I would rather do "something big" and go out with a bang, rather than merely survive until I die.
The wall itself is not exactly "something big" per se, but making it has brought to the fore the importance of a legacy. This wall is likely to far outlive me. Many other people will touch it, sit on it and enjoy it (or maybe even hate it) long after my stint in this life will be over. Fellow earthlings who are not yet even a twikle in someone's eye will interact with this legacy of mine. I won't personally achieve immortality with it. In fact, it's likely that the wall's "author" will fade into anonymity in a generation or so. But it's still something I made with my own hands and it will be around a while - comforting and supporting future generations.
A "future present".