I'm starting to look for new sources of learning

I would say that is probably the #1 thing to help get the kanji actually remembered in a useful way – more context around where it appears and how it is actually used.

Sometimes it helps to check resources like jisho.org for more compound words using that kanji (I also like https://eow.alc.co.jp/ for example sentences with good English translations), and put those in the custom “Notes” section for the kanji for yourself. Also definitely start trying to expose yourself to more natural Japanese! Either via textbooks or something like NHK Easy News, or Satori Reader.

One nice thing about WaniKani and the reason I continue to use it even though like @Ayara012 I also studied Japanese via formal classes at college level is because WK accompanies each kanji with relevant vocabulary that cover at least the most common readings for it, which it what really helps to cement them for me. I still find myself having to dictionaries if I ever need to know how to write a kanji but I am so much more confident reading than I was before I started using WaniKani, and I attribute most of that to WK as before I had studied Japanese for many years without any such system and it never really worked.

As an alternative resource, if you want more/different mnemonics, or kanji presented in a more “bottom up” structural order, maybe check out “Remembering the Kanji” and/or associated community site https://kanji.koohii.com/ (you don’t need the RTK book to use this site, but most of the mnemonics do reference the ones from that book) or my personal favorite kanjidamage.com (WARNING: many mnemonics very crude). However, neither of these are based much more on historical etymology than WK.

I’d also echo the recommendations for the Keisei Semantic-Phonetic Composition script, as well as @pm215’s recommendation of Henshall’s Complete Guide to Japanese Kanji if you really do want the original etymology and think that would help you.