I'll go with a more unorthodox answer, other than "we need a striker". One of the main reasons we don't score more goals is the goalkeeper. In before the GK is there to make saves
Due to the fact that we have a GK that won't leave his line and isn't comfortable with the ball at his feet, we have to compensate by playing our whole team deeper to protect him from crosses into the 6 yard box, or from his poor long kicks that usually cause us to lose possession. As a result, not only does that invite pressure on our back 4(which requires certain CMs to drop deeper to cover our CBs from being exposed), but also increases our transition distance from defense to attack.
Here is a reddit post showing the average defensive line through the season: Man Utd have an average height of 41.52m(bottom 3) vs City are the top(51.69m) and Arsenal(50.82) in 2nd. Next up are Liverpool, Newcastle, Brighton and Brentford.
https://www.reddit. com/r/reddevils/comments/124je6c/pl_2223_average_defensive_line_height_for_each_pl/
Why is that important to our attack?
Not only do we have to sit deeper as a unit, but also it takes us an extra 7-9m to reach the opposition GK. As a result, the opposing team has more time to reorganize and press us higher up the pitch, which in most cases stifles our attack.
I believe with a more courageous GK who isn't afraid to leave his line and string a couple of passes, we will see a drastic improvement in our build up phase, which will allow us to better control games, have more possession, create more chances and and score more goals.
This whole ping pong football we currently keep playing can only take you so far. If we want to start scoring more goals, we need to start dominating possession, and no better place to start than at the very top, the GK.