I think most of us here are so removed from being "new players" that we have forgotten what makes it easy or difficult.
Or what's appealing, sure (I recall harboring some hearty skepticism in the playtest when Mearls started going on about reaching back to early experiences with AD&D to get insight into what would make 5e appeal to new players - being a new player in the 80s or 90s has gotta be very different from being one today!). And the dynamics at the table can have a big impact. But, while 39 years (yeah '80) of experience separate me from my new-player self, only the width of a table has separated me from actual (no scare quotes) new players, since Encounters first got rolling in 2010 (well, not /first/, I came in with the second season).
Anecdote, not data, but I taught a couple of 13/14 year-olds …
Cynicism, not data, but I've noticed that any characterization of an RPG as complex, unwelcoming, complicated, 'hard' or what-have-you, almost instantly conjures an anecdote from someone about a young person mastering it effortlessly.
I have to consider it evidence of youthful enthusiasm rather than any quality of the system in question, since I've noted the phenomenon with quite a range of systems.
For my own experience, I ran a lot of introductory 4e games and played & ran Encounters which included both new & casual players, and special introductory games & Encounters/AL for the first few years of 5e (until health issues kept me from attending my usual cons). And, yes, IMX, I found that 5e was more welcoming to returning players (who, yeah, tended to be 'older'), who found in it what they expected from D&D, while 4e was more accessible to new players (yeah, some quite young, but plenty of adults, too) without preconceived notions.
That's not to say that 5e isn't accessible, especially at a mixed table with an experienced DM and/or player or two to set expectations and explain things:
getting that just-right balance between acceptability to established fans and accessibility to newcomers is the great accomplishment of 5e there's no overstating the difficulty, importance, or impact of that accomplishment. But it is a balance, it's less accessible than 4e was /and/ it trains new players to have similar expectations & attitudes to established & returning ones. That was my actual point, that 5e represents a return to the feel of the classic game, after a really quite short experiment, not just a pendulum swing or cycle - the 4e style of D&D isn't coming back.