I read a bit recently that described thanks as gratitude for that which one did not earn (to which I would also attach, 'deserve'). In my mind, this perfectly fits the Pilgrim's myth which we iterate each year at this time: the benevolent stranger gives the weary passenger a bed, a roof, and a loaf of bread. The myth survives (I hope), because it still occurs. Those without obvious merit and means are given means without regard for merit.
For my own part, I know that I owe much to the charity of friends and strangers. Strangers have saved my life on many occasions. One man out of thousands rescued me from the side of a highway and brought me home. One man pulled me out of the road before a truck passed. One asked me to wait; and another to hurry. I have countless times been guided by the vision of others who had the opportunity to see the world in ways which I could not and the wisdom and goodwill to advise me a better course.
It's easiest to imagine the most dramatic of these little salvations, because they etch themselves so easily into memory; but I fear that I forget the more important thanks which ought be offered to those who toil beneath the obvious.
We are spiders upon a great web, spun and spinning by all those we know; traversing it as though we were the maker.