You can't fault Ole for playing the front 4 or front 5 including Bruno because that was the crunch time of the season and the players were challenged and they stepped up. The players and coaches got them across the line. You have to be able to rely on your best players and test them. They all passed that test, but it showed the weakness of the overall squad. No chances can be taken because the other players are up to the task at hand.
No way Ighalo was going to start over Martial, who has been one of the top players across the PL and European competition since the restart. I can understand playing a different formation, but United really weren't in position to tinker around that much. There was a big job and you have to stick to what got you there. It worked.
Lingard and James will have to start throughout the upcoming season, but at what cost? You have to hope that the other players can keep a good level of consistency and performance, but it remains to be seen if Rashford, Martial, and Bruno can sustain their performance and output levels. That's what separates the good players from the great players, consistency of a high level. And it remains to see if/how James, McTominay, AWB, Pereria, improve. If Lingard somehow regains his form and confidence of 2018, he'd be a great squad player. But from the past 12-14 months, he's been pants when he's been asked to carry a heavier load.
Getting Sancho would be ace, but still need to improve the quality of the squad in order to use it effectively.