That’s how I felt when reading Braiding Sweetgrass 
I think even in the first chapter, I was in tears!
I’m sorry the book wasn’t what you were expecting I can say from personal experience that researching any Celtic lore or stories is going to be just like the book. There are very few written stories from that time period, and what is written was transcribed by Christian monks. Celtic lore is an oral tradition, so most stories are passed down via word of mouth.
I hope you can find a book that better suits what you’re looking for!