I'm not sure you could be more wrong if you tried.
Rey, Finn, Kylo, and Poe are among the most popular characters in all of the SW franchise,
And yet stores since 2015 have put more emphasis on advertising the 1977-1983 movie character range, with more of the new era characters not even being sold in the clearance section? In 2015, sure, it made sense, Ren with the stupid helmet and and the others were not yet established - nobody knows until the movie is aired, not even for cute collectible BB8 And Adam Driver does magic with some of the dialogue given, an unpredictable menace for sure. Actually, yeah, Rey, Finn, and Poe are well acted. The casting agents picked winners every single time in my book. Nobody's wooden, everybody is making their characters feel sincere despite the mimeograph non-script that was TFA. The actors are what kept my interest, they were good and one-upped where the plot was failing.
So I lost what point I was trying to make since my anecdote is on par with yours. But neither of us cited any source material. I'd seen one video but I'm not fond of that channel and I don't namedrop channels I dislike after a certain extent. Well, to be fair I forgot the outlet's name but I didn't need them to tell me what I had noticed firsthand in 2015 in terms of the legacy characters being given prominence (and, no, a primary trilogy movie series should be telling us, including the casual viewers, why C3P0 now has a red arm instead of getting everyone to waddle down to find the esoteric comic release. C3P0 isn't a side character. nor is this an anthology or secondary set of stories. (I don't work in the industry, I couldn't begin to compete with the professionals like Siskel and Ebert, but some of this seems pretty straightforward stuff!)
with Rey rivaling Leia in popularity amongst female fans in general and eclipsing her in popularity amongst younger girl fans.
Didn't know there was some sort of contest going on or that females can only have female popular characters or males only being allowed male characters? And, yes, most young children are more likely going to relate to someone closer to their own relative attributes compared to the grandparents. There are exceptions but there's no such thing as 100%, let's see some graphs and underlying context. It's no different than how most awkward teenage boys found to be more relatable to Wesley over Picard even though adult fans all hated Wesley. Get rid of the kid and then the dynamic changes, since kids will still watch shows that don't have people just like them in it and find someone else to relate to or appreciate more than the others, personality can sometimes eclipse age relational value. Otherwise would TOS have lasted a third of a season, never mind three whole seasons? Never mind kids of all genders watching Wonder Woman and finding her to be a positive and action-packed role model, plenty existed in the 1970s and 1980s and Lynda Carter certainly felt a passion for the role, which helped divert people from some of the more insipid plots (e.g. many from season 3).