I only accept Last Jedi as a standalone and not an extension or Sequel to Return of the Jedi and certainly not a part of a trilogy. But there are actual story beats within it, even if disagree with some of them. JJ did Star Wars greatest hits and tried to make fanfilms. Nostalgia pieces. Without taking any risks. Without any narrative heft, no worldbuilding. No exposition as to why our heroes fell and failed. You just have to accept they were replaced by new Disney heroes.
I think that TLJ is not that much more than a remix of TESB with a little ROTJ thrown in. Only really two new concepts are at play in it, and even then it’s riding on TESB/ROTJ concepts. Luke being a despondent, bitter Jedi is one of the new things, but the mentor who doesn’t want to train the mentee is from TESB, Yoda resists training Luke, the only difference is that it’s about Luke why Yoda resists (while in TLJ Luke is the reason Luke doesn’t want to train Rey, I think another part of the movie, among a few others maybe more, that works in stripping Rey of much of any voice or agency as a character within the movie), even then they’re both still encouraged to mentor their new apprentice by old ally’s from their past. Kylo killing Snoke and taking over is another difference, though that’s more at the end and still basically what Vader did in ROTJ, only real distinction is that this is a swerve away from Vader wanting to overthrow but when he does so he turns away from villainy, Kylo still staying a villain.
The Poe plot is technically newer, but it and Finn and Rose’s plot I think is mostly the Han and Leia plot from TESB split in two, with more people, and to me, dumber. Rebels are on the run from the empire, seek out assistance from someone, who betrays them and turns them over to the empire. Some details are different, but it’s more similar than not I think.
Though, I do think that story is, at least, more consistent than TFA’s story of “find Luke/map to Luke… wait no, rescue Rey and destroy suddenly appearing starkiller base”.