A lot of the elfy stuff is hidden in codexes and asides. If you played through DA:O and DA2, didn't ever play an elf origin, and never read the codexes, I'd be unsurprised if your knowledge of the elves was just 'uh, don't like humans, centuries of oppression, they had some gods once maybe, magic mirrors???'
I think DA:I is the first game where the elven pantheon is mentioned extensively in the dialogue. But yeah, it should have been obvious for anyone with half a clue, if only from noting Flemeth's connection to the dalish as Asha'bellanar, that this is a plot that's been in play for a very long time.
I sometimes wonder whether it'd have been better for Flemeth and Morrigan to both have been elven, rather than human, but I reckon people would have guessed 'oh, she's an ancient elven god, obviously' much more quickly.
It's funny, I started the series with DAI and to me the game is all about elves. Maybe magic, but mostly elves. I remember not understanding at first why everyone was making such a big deal out of the Wardens.
Oh, I can imagine

Adamant must have been really confusing/weird.
Honestly, most of the plot lines set in Orlais have had 'well, but the elves' at the core. The Masked Empire, Wicked Hearts, What Pride Had Wrought - actually, just anything with Corypheus really. It's quite exciting they're exploring the dynamic as a plot point rather than just leaving it as a detail.