Openings vs “principles”

Chess Openings Resources for Beginners and Beyond...

https://www.chess.com/blog/RussBell/openings-resources-for-beginners-and-beyond

I'm about 1600 Daily. I only know the first few moves of the mainlines of a few openings. The advice is correct. You should be able to get to at least 1600 with a few common mainlines and opening principles. The important thing is to pay attention to your opponents moves/threats/plans during the opening (and throughout the game). Most beginners lose in the opening because they aren't thinking hard enough about their opponent's last few moves so overlook their threats.

I had a look at a couple of your games and your opponents rarely had a clue about actual opening theory. Your moves were usually logical and in quite many cases you actually did reach standard positions, though with nonstandard move orders (which sometimes means that there is a chance to punish). The lines you were having problems with were early attacks, which need to be defended, but opening theory will not help in that (most of the early attacks are terrible so opening books usually don't mention them). My impression is that somewhere around 900-1000 rating people start to know the first few moves of standard openings and improvise from move five on or so. At that point it is useful to start learning actual lines gradually and why the moves are played. But even for quite a while beyond that rating range openings rarely decide the game, it is usually blundering a piece in the middlegame.

My general opening book is van der Sterren's Fundamental Chess Openings, which contains main line theory of all major openings, lines usually end around move 10 (books on individual openings go way further). It contains enough opening theory for a club player and reading it also makes it more easy to follow top level chess games.

Learning openings is something you slowly layer over time. You start by following principles and not knowing openings by name or theory. Then you realize that you get these same few "variations" often like 1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 and then you look it up to discover that this is the "Four Knights Game." From there you slowly expand by playing games and realizing that you made a bad move somewhere, you learn a stronger line and then "add-on" to your theory. This process is usually one move at a time and that is how you build up to long lines 15+ moves deep, but this won't happen anytime soon so opening principles is sufficient.

It is easier with examples sometimes, but I don't think it is a bad thing to glance a little into openings at any level - it just shouldn't be the focus until around 2000+ rating and most players never get that high.

around 1000 I started learning actual theory. I'd say i only started using it around 1300, but I still manage to get good positions because I have 10 moves of my favorite openings memorized

+1 and this is about the pace I'd expect based on ratings. 10 moves deep is a little far for 1500-ish but not unreasonable and certainly understandable for your favorite openings. I started using opening theory more so around 1300 just like you too. I feel like sub-1000 is mostly learning the rules, basic strategy, not hanging pieces as much and opening principles. Then up to 1200 is pretty much the same but the player is better at using things like opening principles. 

1300-ish you start actually using a little bit of openings and a lot more theoretical endgames. By 1500, you have a strong grasp on all of these things. 

1600+ is about when you begin getting introduced to positional motifs such as weak squares and outposts while raising your overall knowledge on everything (endgames, openings, middlegame plans, tactics etc.)

1800+ basically is a 1600+ player with more rounded nuisances into positional motifs.

Between 1800 and 2000, I think it is mostly getting even deeper into position by means of pawn structure, pawn breaks/levers and starting to get more serious with other things not specifically studied prior (perhaps calculation training, visualization training, starting to consider deeper opening study and so on). 

I can't speak for higher ratings since I'm not there yet, but the way I understand it is that 2000+ is more about openings/real deeper opening study as well as deeper pawn structure ideas. Everything else higher is probably individual based on their personal strengths and weaknesses or concepts that resonate with them differently

well tbf I learned a lot of lines but my endgames suffered in return. I'm a very strong opening player but I struggle later on. So yeah I agree @KeSetoKaiba

Although I understand the positional motifs of my main openings already as a 1550. Just not anything crazy

Yup and that is what is expected. That is about where I was at 1550-ish too. Keep in mind, my rating comments are general observations I noticed to be true for most players, but everyone has their own strengths or things they need to work on too. 

You do not generally lose because of the opening, you lose because of blunders or middle game tactics. Play the opening slowly and thoughtfully according to the principles and you will be all right. Focus on tactics and endgames.

Follow the principles is key if you want to improve. I am not sure what you mean by being destroyed by the bots. If you can describe your problem better, I could help you better.