- Luke attempting suicide only to be conveniently saved due to plot armor
He wasn’t committing suicide, he was trusting the force.
I always got the impression that Luke sacrificed himself in order to not fall to the dark side (this is clearly the case in the novelization, which was Lucas canon). And I hardly see how him being saved by the plot is a bad thing. Plot convenience is kind of a staple if SW, and part of what makes the OT so much fun. I mean ANH is filled with these; Artoo and Threepio conveniently being reunited by the Jawas, ending up at the Lars farm, the R4 droid having a bad motivator, etc.
Luke’s sacrifice makes sense as a part of his character development in ESB as well, but his death would of course have cut the trilogy short, so naturally he conveniently survives.