too much theoty

I've got a book on ruy lopez from my couch, reading the first 6 pages and analaysing (only by the book, no added move), gave me the following (The main line is just the last one analayzed)

(if you don't understand then use movelist)

seeing this is only the first 6 pages out of 112 I get that there is too much theory for someone like me to remember it all and the ideas in each variation for a few different openings

Yes, but who says you have to know all this?

Play a game, look up the theory after the game. Repeat.

Only when you play opponents who know similar amounts of theory (perhaps at 2400+), AND this variation will still be topical and in your repertoire (a long shot, for all 26 moves) will you need to know it this far.

For now, why try to remember it?

When using an opening monograph, the place I start is to look in the variations index.  Play over those moves, and each time ask yourself: "what would I do?"  You will probably find that some moves come naturally. 

From there, study the sections where the moves that come naturally to you. This will lead you toward lines that are compatible with your individual taste. 

Opening books are not meant to be read from cover to cover; from page 1 to page 351.