I got terrible at chess


I looked at some of your games and I think you could go down a rabbit hole with openings and tactics. At your level though, I don't think it's needed.
Some things I noticed.
In many of your openings, you are putting a pawn in the center of the board and then on your 2nd move defending it with a bishop. As a general principle, pawns should be defended by other pawns, and in the opening you want to defend your central pawn with a knight. Your bishop is a long range attacking piece. And limiting it's potential by essentially turning it into a pawn isn't helping your game.
A lot of your issues are board awareness - not immediately seeing that an opponent's piece is hanging and snatching it up, or moving your piece to an unsafe square. You're playing a lot of rapid which is good. Before making each move look around the board and make sure that you aren't hanging pieces. Likewise, look for any pieces that your opponent has hanging. I think if you made checking for hanging pieces each turn a habit it would do a lot to improve your game.

Learn and apply the most important principles of chess. - (core of my teaching)
Always blunder-check your moves.
Solve tactics in the right way.
Analyze your games.
Study games of strong players.
Learn how to be more psychologically resilient.
Work on your time management skills.
Get a coach if you can.

HeckinSprout makes good points. I'd advise anyone under 500 NOT to sacrifice pieces! Follow Botvinnik: sacrifice your opponent's pieces. Chess is mostly a materialistic game.