This can certainly be nitpicked, but some of the OSR (or at least, pre-3e) stuff I see:I keep trying, and I just don’t see the OSR in 5e. What about it takes folks back to their old school gaming days?
1) Frontloading of mechanical choices. Once you pick race, class, subclass, you really don't make a lot of choices when you level. You just gain new abilities. (Less so with feats and multiclassing turned on, but still much less overall than 3e and 4e).
2) Simplification of combat. You can move and either cast a spell or swing a weapon, and occasionally do something else. Broader options do exist (there's that 3e and 4e DNA again), but there's nothing like the trading of move actions for other options or full-round actions of 3e, or the menu of standard/move/minor actions of 4e.
5e is like the half-sibling of every other edition, you can see the resemblance if you look, but it's still obviously its own thing.