I think Arsenal provides an interesting case. They finished 8th in 20/21. In 21/22, they brought in Tomiyasu, Lokonga, Ramsdale, White and Tavares - a group of players without much lasting impact, most of whom were relatively cheap, but they plugged holes and addressed obvious problems. That let them move from 8th to 5th.
Then in in 22/23, they brought in Jesus, Zinchenko, Vieira, Trossard, Jorginho and Kiwior. Not one of those players are still in their first XI (or really ever were), but they plugged the remaining holes and addressed obvious issues. They were all significant signings, but not really big ones. That allowed them to make the jump from 5th to 2nd.
It was only after that they started adding the pieces that became integral to their championship team. Rice, Havertz, Timber and Raya in 23/24. Calafiori and Merino in 24/25. Zubimendi, Eze, Gyokeres, Madueke and Hincapie last summer.
I think there are some interesting takeaways from that story. I was always mystified by their transfers in 21/22, because it seemed obvious that the players they bought were not of a calibre that could make them important pieces of a future contender, which is what they were building towards. But what they seem to have done, and which seems to have worked, is to progress in stages. Their 21/22 additions helped make them a more functional and complete team and to regain competitiveness. Their 22/23 additions then built on that to upgrade in key positions, bringing them much closer. And from there on it's been a question of marginal improvements in already strong positions, and expanding quality depth, culminating in last season's title.
If you place United in that trajectory, I would say we're at more or less the same stage Arsenal was in 22/23, and perhaps even a bit behind that. We are still plugging holes and fixing issues rather than upgrading an already functional and balanced squad that is competitive but not quite a title contender. Entering this window, we did not have a credible backup goaltender, were a man short at LB, three men short in central midfield, had a rather unsettled central defence (anyone want to bet which two CBs are the regular starters two seasons from now?) and had obvious issues at the RB and Striker positions. Our transfer activity must be expected to be geared towards addressing those multiple issues, which in practice means it's not going to be big money star players, and not not necessarily players with a long and important future at the club either. This is what building in stages looks like.