I recommend the marshal attack (jk) but seriously if you’re a beginner just play something simple like an italian as white or e5 e4 as black
What chess openings would you recommend to beginners?

Start with the Italian. Play through all of Greco’s games that are the Italian. There are not many. Learn them well. Then, look at Morphy’s.
https://www.chess.com/explorer?color=white&playername=Gioachino%20Greco
Maybe on this site: https://www.chessgames.com/perl/chess.pl?pid=72111&playercomp=white&opening=C50+C53-C54&title=Gioachino%20Greco%20playing%20the%20Giuoco%20Piano%20as%20White ?
Yes. Chessdotcom used to get testy about links to other sites, but that one is much easier to use. It also has more Greco games than ChessBase. I’ve added one or two from history books, as well as identifying some credited to Greco that are really Polerio.
Here’s another resource: https://www.chess.com/forum/view/game-analysis/a-greco-game-that-you-have-not-seen

Introduction to The Italian Game & Evans Gambit...
https://www.chess.com/blog/RussBell/introduction-to-the-italian-game

Hi, not an easy answer. In my opinioin if you are already familiar with some openings, the best use of your time would be just to play them better -unless you don't have an established repertoire, or play doubious openings. Again in my opinion, at your level you should focus more in expanding your general chess skills rather than in opening theory.
Anyway if I were you , I would keep things simple, for instance I would open the game with white pieces with 1.e4, and with black pieces I would meet 1.e4 with 1...e5, and 1.d4 with 1...d5.
Good luck!
I know it is probably not the best approach but I like to mix it up to keep it interesting. I stay focused better that way.
With white I play the 4 Knights (Spanish or Scotch), Scotch (gambit or without gambit), Queen’s Gambit…
With black Caro-Kann or the French against E4 since I don’t like playing the Italian too much. Sometimes even the Sicilian, but it is very complicated.
Against D4 mostly D5, but sometimes Nf6.
As long as it is a solid opening it should not matter too much.