Finally, after failing to learn years ago (probably from lack of patience), relearning, and much practice - I have single crocheted a scarf! Maybe not so impressive, but the rows are pretty even, no mysterious dropped stitches or tightened tension, and it is a decent length to be worn. Version 1.0 with this yarn actually came out well too, but I'd made it too wide so there wasn't enough length. Cue ripping out all the crochet and starting again. No wasting yarn here.
The yarn is a Bernat cottontots yarn - which is 100% cotton - with the color name "sunshine" that I had bought many years ago intending to crochet a hat. Not sure how I intended to do that with my then complete lack of crochet ability, but hope springs eternal. So here, in all of its not-very-interesting glory is my first successful crochet scarf, folded for your convenience.