This book I'm using to learn kanji is probably right down your alley. Breaks down a little over 2k kanji into elementary school levels. It has a preface about the origin of the language, and every individual kanji has a small description of it's history and how it was derived from ancient script. (https://www.amazon.com/Complete-Guide-Japanese-Kanji-Understanding/dp/4805311703)
I got the first ed. of this back in the 80s:
https://www.amazon.com/Complete-Guide-Japanese-Kanji-Understanding/dp/4805311703
and it was pretty decent for what you ask.
The current version has been updated with the 200-odd additions to the general use kanji since the 80s.
By the way, a new revised edition is coming soon, which seems to be a bit more explicit about the sources in the entries.
Definitely, I agree about Duolingo. I've done some of it but I know someone who completed the entirety of the course. It doesn't go beyond anything you mentioned. If you want to learn kana, it'll do the trick. Couple of key words, sure. Even the last level uses basic grammar and sometimes isn't fact checked properly. Duolingo's Spanish class on the other hand offers more, and is better supported. It's free, so I'm not against it, but definitely isn't as efficient as other sources.
If you want to learn kanji, there are two major lists out there. The Jouyou kanji and the JLPT kanji. The first covers about the same characters as the second, but the order is widely different. Following the kyouiku kanji list (All lists are readily found online or through Wikipedia) will give you the first 6 grade levels of kanji, and bring you to about half of the jouyou (General use kanji). I recommend following both as the JLPT racks up difficulty much faster and grows exponentially with each level, whereas the other maxes out at 180-200 characters per year. Alternating will add more steps to the ladder, and give you a much clearer set of goals.
I purchased a book containing the general use kanji, and I now use it to cross-reference the JLPT required kanji as well. If you follow both lists to completion, you might end up knowing an extra 100 characters, but for the most part they're about the same, and each cap at around 2100-2200 characters, at which point one would be fluent to a business level or more.
This is the book, ~20USD on Amazon: https://www.amazon.com/Complete-Guide-Japanese-Kanji-Understanding/dp/4805311703
Kanji is probably the most difficult thing to get good at, but its resources are the easiest to find. You won't need to spend much. A bunch of websites also teach the stroke order, so if ever you are stuck, searching the kanji itself will grant you a lot of good results. Verbs are few, and exceptions are only found in two of them, but grammar and some odd adverb uses might be really difficult to pick up on without using books, so I would recommend eventually complementing your studies with some. The Minna no Nihongo book series is also very good, but is fully in Japanese. If you can read kana you should be able to get the ball rolling there. I heard very good reviews. I also believe its price point is in-between the two other book series I mentioned before.
For now, a Google search or following lists on Wikipedia will do you pretty much just as good as any book for kanji. Very easy to have tabbed on a phone as well. I like Tanoshii Japanese's stroke order pages and I've started looking through Japanesetest4you's grammar examples for more out there stuff.
Hope this helps!! :)