tl;dr
Replace all the things, buy a new bike.
If parts of your drivetrain are really worn then only a partial replacement will be throwing good money after bad. So replace chain cassette and chainrings may well be best.
@dancing james started
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tl;dr
Replace all the things, buy a new bike.
If parts of your drivetrain are really worn then only a partial replacement will be throwing good money after bad. So replace chain cassette and chainrings may well be best.