I Truly Do Not Understand What I Read

The first movie I ever took my kiddo to the theater to see was the DreamWorks film, Home – with Jim Parsons and Rihanna voicing the main characters. Years later, our family still adores this movie and I tear up in the same spot hundreds of viewings later.
Turns out, this film is based on a book – The True Meaning of Smekday, by Adam Rex. Alrighty, let’s dig in! I’m all for source material!
I just finished this 400 page… scifi? sci-comedy? YA scifi-comedy experience and was left thinking, “What the f*ck?” I’m curious as to the mental gymnastics the folks at DreamWorks had to complete to adapt this into a children’s movie… and I’m really not sure what I just read.
As told from the point of view of Gratuity Tucci, she is writing her experiences on the day the Boov (alien race) took over her planet and were then nearly destroyed by the Gorg (another alien race). I think the Rex is trying to make a statement about colonialization and how indigenous people are cast aside and history is rewritten by the “winner”, but I found myself completely caught up in the description of various space ship tools, confusion over what anyone was actually trying to do, and awkward dialogue to let any larger lessons reach me.
Maybe I’m too attached to the film and should never have approached the source material? Maybe I’m just tired and looking for simpler readings for entertainment? I just can’t remember the last time I finished a book and looked at is as I closed the cover and went, “Wah???”