While I think 5e is very much its own thing, it does feel a lot like 2e + 3e in a lot of ways. Granted, that is an entirely personally held, highly subjective opinion.
I think 5e dispenses with the build-focus that dominated the 3.x game (I enjoyed the options/customizability early on...but I found it went wildly out of control once 3.5e hit). Mainly (to my perspective) that occurred with Feats. Originally loved the idea, but the more I played and saw the system in action, the more it showed its nature to me...slow, feat trees mostly became 'take this line of general junk to finally get something cool only to see that by the time you got to the 'cool', it was no longer cool, not all that useful, not fun, more junk, etc).
3e gave the game the central core d20 mechanic (which 1e/2e had for some parts, but 1e/2e was also a pastiche of various, often nonsensical, mechanics). 1e/2e core combat mechanic was actually the d20 mechanic, but with a very sloppy/ugly way of doing it.
One of the big things I find 5e took from 2e was the narrow approach to classes. In 1e/2e, Fighter Bob was, mechanically, the same as Fighter Doug, who both looked an awful lot like Fighter Pete. The differentiation was mostly in role-play, less mechanical (the only real mechanical differentiation was with weapon/nonweapon prof choices and what armor fit the player's vision). Some classes offered a touch more mechanical choice, but ultimately the real differentiation was up to the role-playing. The Kits in 2e really offered some mechanical differentiation within a class, but they were all over the map as far as quality/playability. Some were really well done, some really poorly done, some made one wonder why even bother, and some were (mostly poor) attempts to reintroduce classes lost in the 1e -> 2e transition (i.e. assassins, cavaliers, monks, wu jen, kensai, samurai, etc). 5e's subclasses are its interpretation of 2e's kits (I find they're more akin to 2e kits than say 3.x prestige classes any way).
So I think 5e is its own, unique thing, but I find its bones are definitely an interpretive melding of 2e and 3e.