Best openings for beginners - as white & black

For what it's worth, you might even pare that number down a bit. As White, since you can set the initial opening, I'd suggest sticking with the major Queen's Gambit lines. Learning those as Black also will help understanding. Since as Black you have to initially respond to whatever comes your way, to answer what lines you might study - what approach suits you best? Positional play, tactical maneuvering, gradual attrition? Perhaps playing more unusual openings may help offset any disadvantage you may feel from lack of memorization.
No need to learn multiple openings, learning 2 for Black (i.e. response to e4 and d4) and 1 for White is sufficient for a beginner.
I will recommend the Queen's Gambit for White. For Black, Caro-Kann against e4 and KID (King's Indian Defense) against d4.
Fairly straightforward openings.

First of all, at your level, openings are the last thing you need to spend time on. Learn and practice the opening principles and then master basic tactics.
For White, start with 1. e4. For Black, play 1...e5 against 1. e4 and 1...d5 against 1. d4.
The reason I recommend 1. e4 to start with is that 1. d4 will tend to lead into more strategic games while most of your games (right now) with 1. e4 will tend to open up the middle and allow you to develop your tactical awareness.
I would NOT recommend the Caro-Kann and King's Indian Defense for someone at your level as they require understanding pawn breaks, which you most assuredly are not ready for (and contrary to what someone else said, neither are "straightforward"). Along those same lines, I would not recommend the Sicilian for you right now as it will have very forcing lines that require more tactical awareness than you currently have. Start with the classics and move on from there.

Look into playing the Reti or the King's Indian Attack as White... you can get a decent enough game against practically any Black layout.

I played the Sicilian Najdorf and King's Indian Attack as a 1400 player.
It doesn't seem to have hurt my chess development much.

I agree with what you said, but i played Kings Indian Defense and Attack since the begining when i was 800 and still managed to come to a 1400-1500 level and im still improving. The thing is that in lower rating games your opponents also dont understand pawn breaks or closed positions, so they are not likely to play with closed centre and getting into a king and queen sides of the board race. Modern approaches often catch them of guard, and with various discoveries and attacks that the knight and bishop can make, it often becomes a great opening. Also modern openings are very flexible so you can play similar first few moves almost every game. Similar with Caro-kann, most of the principles rely on what white does with the e4 pawn, whether he takes the pawn, pushes it or leaves it there.
Also i definitely agree with the Sicilian, maybe Catalan too and similar openings, too many variations and complications so its better to start playing it once you get to atleast higher intermediate level.
The point is not that it cannot be done, but rather that I do not recommend doing it. The issue with the Caro-Kann and KID is that you end up in a very closed position quite often and will get blown off the board quite often without having the slightest clue as to why. Conversely, in the Open Games, if you get blown off the board it will be quite obvious as to why.
To give an example of violating my own recommendation, I have played the Sicilian from day 1. I have always loved those positions, even when I got crushed. But I knew going into it that I was likely to lose often and did not mind that. Many people cannot handle losing repeatedly for years before they start to understand an opening.
Hi, I've been playing e4 and specifically mostly Italian game. I'd like to expand my repertoire to have 2-3 openings both for white and black. I'm really bad at memorization so long sequences are probably not great for me. What would this community advise as 2-3 openings to work on for both white and black?