Not sure if you've heard the Amoyal podcast where they spent a fair few minutes on United (Pilib de Brun was featured). Some of the things they mentioned:
1. United have been preparing for months
2. The club has contacted at least 25 players this window working on various scenarios
3. Separate lists were made assuming we'd be in EL vs assuming we'd make the CL
4. Plans were affected and we've had to change targets at times
5. Belotti was ruled out on price after at one time being ahead of Morata on our list - but now we're looking at Morata primarily
6. Perisic was initially on List 2 (Europa) but got elevated - probably because of the Griezmann situation
7. We are continuing to work on a bunch of targets all at the same time and nobody really knows where we are on any aspect as info is not available
In this light, there's a good chance that we have indeed contacted in some manner a large number of the players we're linked to constantly. There's no reason to believe we have not touched base. Whether we are serious or not, can't say. That said, look around. Virtually no club has been making big signings (Bernardo Silva is not - yet, at least, worthy of classifying as a big signing). The market at the top end generally sees moves happen rapidly after the first couple of moves are made and I think everyone's just waiting for that to occur. That's also what will set baselines for price, so it's no surprise as sellers watch the "market rates" and continue to hold out for as high an amount as possible in the hopes that the baselines will be high and buyers remain wary and hold back waiting for lower floors to become apparent.
That's also probably why United in particular are holding back. If we were to sign Perisic for 50 Mn, it's virtually certain that the Morata price won't fall by much (if at all) while other prices will also be staggeringly high. Business logic...
It is interesting that no big names have moved yet this summer. Sanchez is still at Arsenal, Lukaku hasn't moved yet, Bellotti hasn't been sold either.
If we had bought Griezmann I'm sure the subsequent transfers would've been a bit different.