I like these kinds of names too. I think if you want to avoid super popular or trendy you need to avoid specific sounds/styles more than individual names, especially for girls. As pps have said, even the most popular names aren’t that popular nowadays, but there are definitely certain sounds that crop up a lot among the small children I know. DD, 4, has just started Reception, and in our London suburb it’s:
Short, vowel-heavy names: Isla, Aria, Myla/Mila
L names: Lily, Luna, Lyla/Lila, Lyra, Layla
Any permutation of Eva/Evie/Edie/Ava/Ada/Ivy
Long, frilly names: Arabella, Isabella, Ophelia, Arianna
Granny chic names: Mabel, Olive and Martha seem to be the favourites here
For boys it’s still the cheeky chappy nickname names that dominate: Charlie, Ronnie, Albie, Alfie, Archie, Lenny
Most of the classic-sounding names suggested above would make a refreshing change, especially anything ‘spikier’, less cutesy/frilly or more solid sounding for girls. I like Hazel and Rowan is a good call but watch out for popularity - lots of boy Romans and Rowans around.