Spending doesn't solve anything. Haven't the last few seasons proved that to people yet? The way to improvement is time and a good manager. We have lots of quality players. Our performances recently demonstrate that much. Now we should primarily stick with what we've got, and only buy to replace an old player or fill an actual hole in the squad (not just a position where impatient fans think there's greener grass to be had elsewhere.)
If Jose's not willing to start blooding a youngster, we can look for a quality replacement for Carrick. As for Ibra, it's ridiculous to have both Martial and Rashford in the squad and be too cowardly to give one of them a proper go as his eventual replacement. They're two of the best young talents in world football. But they'll never fulfil their potential until someone actually gambles on them. You want a 20-a-season striker? Try actually playing one of them as our striker.
Whilst I echo some of your post we do have gaping holes in the squad. Carricks replacement being one of them. When Depay Morgan Bastian and Darmain get moved on suitable replacements need bought but in the mean time we must make sure we get in the top 4 and we need a midfielder plus someone to help ease the goal scoring burden from deep on Zlatan imo.