OP, I'm sorry to disagree with you, but I've got plenty to say about your list.
Elvis - very handsome and charismatic man who had a very beautiful voice, but he cheapened his brand with dismally bad films and was a complete embarrassment by the 1970s. After he died, he was elevated into legendary status by his business-savvy and opportunistic estate's managers. Still, many of his songs are classics, so we can reluctantly consider him a good addition to this list.
Michael Jackson - massively overrated talent (OK voice, catchy but repetitive songwriting), whose mystique was created by his very talented producers and legions of deranged fans, who grew obsessed with him due to his reclusiveness. Few of his songs are classics, but he did change popular music as the visible face of a wider cultural movement. We can reluctantly consider him a good addition to this list, but only because better artists didn't get as much projection.
The Beatles - typical case of opportunism and being in the right place at the right time. Bad musicians and mediocre singers who released lots of bubblegum pop innovatively produced by the truly talented George Martin, and then did become insufferably pretentious. Still, the DID change popular music and improved as time went by, so I guess that they deserve a mention for that... Still, they were still bad musicians and mediocre singers.
Kurt Cobain - passable songwriter and singer who died at the height of his fame, and for some reason was elevated to legendary status by self-important Gen Xers who wanted to feel culturally relevant by creating their own martyr. His status is completely underserved and he shouldn't be on this list.
Beyoncé - good singer who doesn't deserve to become a legend, because of her mostly awful repertoire. Also, she is only the best of her generation because 95% of female singers since the 2000s are utterly talentless, or have disastrous technique. She shouldn't be included here.
Madonna - show woman of severely limited talent who was a master of self-promotion and surrounded herself with extremely talented people who did all the heavy lifting for her. Many of her songs were huge hits, but few of them are classics, if any. She doesn't deserve to be classed as a legend, because she didn't improve on anything - in fact, she is directly responsible for ushering the age of talentless whoredom in which we live.
Tupac Shakur - oh my God, you can't be serious! He couldn't sing to save his life and, as it happens with all rappers, his music was shit. Also, he was a hypocrite who pretended to be a revolutionary but was very much a part of the status quo, and contributed to normalize trashy thug culture as something liberating and desirable, instead of the result of oppression and social injustice that it is. The answer is NO.
Taylor Swift - WHAT?!?!?!?! Anyone who considers this talentless joke of a tween "singer" a legend, is downright insane. Legends have great voices, whereas this slag can't even sing in tune and her songs are disposable crap of the lowest grade. NO. JUST NEVER, EVER, EVER, EVER.
Prince - he was the very personification of 'The Emperor's New Clothes'. Good voice and good technique, but ridiculously pretentious product of hype whose alleged talents as a multi-instrumentalist and composer translated into most mediocre songs, and some dismally bad heaps os steaming manure - sorry, but anyone capable of vomiting Batdance and Love Song, doesn't deserve o be considered a legend.
Post Malone - OK, you are either completely deaf, or have a flat encephalogram. Only that can explain the fact that you have included this pathetic, wretched creature on a list of legends.