I don't know when I first heard this phrase. I know it must have been as a child.
"Back to square one…" is often heard when something doesn't go as planned – the experiment fails miserably, the job you have held for years no longer exists, etc.
The exact origin of "square one" is uncertain — football (think tea and crumpets not soda and nachos), chutes and ladders, Hopscotch. It's meaning, however, is clear — a do-over, starting from scratch, at the beginning — take your pick.
However, I contend that there is no square one in life. We may climb a ladder or tumble down a chute, but we will never truly find ourselves at square one as a newborn infant.
Setting aside biological impossibilities, you have the fact that we learn from each experience in life whether good or bad. Some might argue we learn more from the bad than the good, but we do learn — and what we learn is not erased with failure, it merely teaches us what not to do.
And if you have gotten through my "Meanderings" and are to this point — congratulations, for you cannot return to square one today even if it all falls apart after supper. You have learned something, however minor; whatever set backs you have experienced can be overcome; and tomorrow brings the promise of a new day and whatever you choose to make out of it.
Now, off to square 743,645…supper.